UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE. 


AGRICULTURAL  EXPERIMENT  STATION. 


MANUFACTURE  OF  DRY  WINES  IN 
HOT  COUNTRIES. 


By  FREDERIC  T.  BIOLETTI. 


BULLETIN    No.    167 

(April,  1905.) 


SACRAMENTO: 

W.    W.    SHANNON,       I       :       :      SUPERINTENDENT    OF    STATE    PRINTING. 

1905. 


/ 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University. 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist. 

E.  J.  WICKSON,  M.A.,  Horticulturist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  C.E.,  Irrigation  Engineer. 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.    (Soils  and  Alkali.) 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.    (Foods,  Nutrition.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.    (Starches,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.    (Fruits,  Waters,  Insecticides.) 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian,  Bacteriologist. 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

A.  V.  STUBENRAUCH,  M.S.,  Assistant  Horticulturist,  in  charge  of  Substations. 

E.  H.  TWIGHT,  B.Sc,  DiplomS  E.A.M.,    Viticulturist. 

F.  T.  BIOLETTI,  M.S.,    Viticulturist. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Field  Entomologist. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

H.  J.  QUAYLE,  A.B.,  Assistant  Entomologist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  Fertilizer  Control. 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 

C.  A.  COLMORE,  B.S.,  Clerk  to  the  Director. 


R.  E.  MANSELL,  Foreman  of  Central  Station  Grounds. 

JOHN  TUOHY,  Patron,  ) 

r  Tulare  Substation,  Tulare. 
JULIUS  FORRER,  Foreman,  ) 

J.  E.  McCOMAS,  Patron,  Pomona,  ^ 

J.  W.  MILLS,  Superintendent,  Pomona,  I 

y    Southern  California  Substation. 
•In  charge  Cooperation  Experiments  of  Southern  California, 

JOHN  H.  BARBER,  Assistant  Superintendent,  Ontario, 

J.  W.  ROPER,  Patron, 


.    University  Forestry  Station,  Chico. 
HENRY  WIG  HTM  AN,  In  charge, 

ROY  JONES,  Patron,        ) 

_.  .  >•   University  Forestry  Station,  Santa  Monica. 

WM.  SHUTT,  Foreman,    \ 

H.  O.  WOODWORTH,  M.S.,  Foreman  of  Poultry  Station,  Petaluma. 


77i£  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, will  be  sent  to  any  citizen  of  the  State  on  application. 


V 


X 


CONTENTS. 


Page. 

INTRODUCTION 5 

METHODS  FOR  IMPROVING  MANUFACTURE   OF    DRY  WINES   IN  HOT 

CLIMATES 10 

AMELIORATION  OF  THE  CHARACTER  OF  THE  RAW  MATERIAL 10 

Varieties  of  Grapes . 10 

Time  of  Gathering  the  Grapes 12 

Methods  of  Cultivation 15 

Pruning;  Irrigation;  Fertilization 15 

More  Complete  Utilization  of  the  Substances  of  the  Grape 17 

Effect  of  high  temperature  in  making  dry  wine 19 

Extraction  of  color  and  tannin 22 

Addition  of  Substances  Deficient  in  the  Grapes 27 

Water;  Tartaric  acid;  Citric  acid;  Plaster;  Phosphates 28 

CONTROL  OF  FERMENTATION 33 

Modifying  the  Temperature .___' 33 

Physical  Cooling  Devices 34 

Aids  to  radiation  ;  Attemperators  and  refrigerators  ;  Ice 35 

Chemical  Cooling  Devices 44 

Sulfur ;  Sulfites 45 

Postponement  of  Fermentation  until  Winter 51 

Fermentation  in  Cool  Locality 52 

Control  of  Fermentative  Agencies 53 

SUMMARY 57 

Methods  Adopted  in  Southern  France  and  Algeria 57 

Conclusions 63 


MANUFACTURE  OF  DRY  WINES  IN  HOT 
COUNTRIES. 

By  FREDERIC  T.  BIOLETTI. 


[This  bulletin  is  the  outcome  of  a  recent  visit,  made  under  the  auspices  of  the 
University,  to  some  of  the  chief  vine-growing  regions  of  Europe  and  Algeria. 

This  visit  was  undertaken  during  the  months  of  October,  November,  and  December, 
1904,  and  its  main  object  was  to  study  the  many  changes  which  have  been  introduced 
in  recent  years  into  French  methods  of  grape-growing  and  wine-making.  As  it  was 
impossible,  in  the  time  available,  to  cover  the  whole  of  the  ground  thoroughly,  my 
attention  was  directed  mainly  to  those  subjects  which  seemed  of  most  immediate 
interest  to  the  University  and  to  the  committee  of  California  grape-growers  who  con- 
tributed part  of  the  necessary  expenses  of  the  trip. 

In  accordance  with  this  idea,  my  observations  had  to  do  chiefly  with  the  methods  of 
wine-making  peculiarly  adapted  to  hot  climates,  and  with  the  methods  of  viticultural 
and  cenological  education  in  vogue  in  France.  Other  matters  of  interest  to  Californian 
viticulture  were  given  as  much  attention  as  was  possible  without  interfering  with  these 
two  main  objects. 

The  principal  educational  institutions  visited  were  the  "  Kgl.  Lehranstalt  fur  Wein, 
Obst  und  Gartenbau  "  at  Geisenheim  on  the  Rhine,  the  "  Institut  Nationale  Agro- 
nomique"  at  Paris,  the  "Ecole  Nationale  de  Grignon"  near  Versailles,  the  "  Ecole 
Nationale  de  Montpellier"  in  the  south  of  France,  and  the  "Ecole  Pratique  d'Agri- 
culture  d'Ecully  "  near  Lyons.  At  all  of  these,  especial  attention  is  given  to  instruction 
in  viticulture  and  cenologjr. 

Experiment  stations  and  research  laboratories  devoted  more  or  less  exclusively  to  the 
same  subjects  were  visited  at  Nancy,  Epernay,  Villefranche,  Nimes,  Montpellier,  Nar- 
bonne,  Perpignan,  Toulouse,  Bordeaux,  and  Algiers.  Visits  were  made  to  the  depart- 
mental professors  of  agriculture  at  these  centers  and  to  vineyards  and  cellars  in  the 
Rheingau,  Champagne,  Burgundy,  Beaujolais,  Cotes  du  Rhone,  H6rault,  Gard,  Nar- 
bonnais,  Roussillon,  M£doc,  and  Algeria ;  the  greater  part  of  the  time  being  spent  in 
the  Midi  and  in  Algeria.  My  investigation  was  very  much  facilitated  by  the  great 
courtesy  and  assistance  received  everywhere  from  investigators  and  proprietors.  My 
thanks  are  especially  due,  among  many  others  to:  Professor  Dr.  Wortmann,  Director 
of  Geisenheim;  M.  Pierre  Viala,  Inspecteur  General  de  la  Viticulture  at  Paris;  M.  L. 
Ravaz,  Professor  of  Viticulture  at  Montpellier;  and  M.  Roger  Mares,  Departmental 
Professor  of  Agriculture  at  Algiers. 

I  was  much  assisted  in  my  investigations  by  the  advice  and  encouragement  of 
members  of  the  California  Viticultural  Club,  notably  of  Messrs.  Percy  L.  Morgan  and 
Frank  T.  Swett,  without  whose  aid  the  scope  of  the  work  would  have  been  very  limited.] 

INTRODUCTION. 

It  is  a  remarkable  but  well-recognized  fact  that  in  the  regions  where 
the  vine  nourishes  best,  that  is,  where  it  yields  the  maximum  crop  for 
the  minimum  labor,  the  greatest  difficulties  are  encountered  in  the 
manufacture  of  sound  dry  wines.  In  a  general  way  it  may  be  said  that 
nearly  all  the  fine  dry  wines  of  the  world  are  produced  in  regions  such 
as  those  of  the  Gironde,  Burgundy,  and  the  Rhine,  where  the  climate  is 
relatively  cool  and  where  the  vine  does  not  attain  its  fullest  develop- 


b  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 

merit  either  of  growth  or  of  crop.  In  the  warmer  and  more  productive 
regions,  if  wines  of  superior  quality  are  made  they  are  usually  sweet  or 
of  sherry  type.  The  dry  wines  of  these  regions  are  of  two  general 
types,  (a)  thin  watery  wines,  such  as  those  of  the  south  of  France,  whose 
main  value  lies  in  their  cheapness,  and  (b)  heavy,  coarse  wines  valu- 
able for  blending,  such  as  those  imported  into  France  in  large  quantities 
from  Spain,  Algeria,  and  elsewhere.  The  wines  of  the  latter  type  are 
not  only  defective  in  quality,  but  very  commonly  unsound,  and  large 
quantities,  in  the  aggregate,  spoil  before  they  reach  the  hands  of  the 
wine  merchant  and  become  a  total  loss  or  are  made  into  inferior  brandy. 
This  loss  would  be  much  greater  but  for  the  use  of  the  antiseptics 
which  are  freely  employed  wherever  the  practice  is  not  prevented  by 
effective  pure-food  laws.  Before  discussing  the  question  as  to  whether 
the  wines  of  the  warmer  regions  can  be  improved,  and,  if  so,  what  are 
the  most  practical  methods,  a  clear  understanding  of  the  nature  of  their 
defects  and  the  causes  of  these  defects  is  necessary. 

The  quality  of  a  wine  depends  on  two  groups  of  factors:  (a)  those 
which  have  to  do  with  the  nature  of  the  raw  material,  that  is,  the  char- 
acter of  the  grapes;  and  (b)  those  which  have  to  do  with  the  way  in 
which  this  raw  material  is  treated,  that  is,  the  character  of  the  methods 
of  manufacture.  Each  of  these  groups  of  factors  influences  the  other, 
so  that  it  is  often  difficult  to  decide  whether  certain  qualities  of  a  wine 
are  due  to  the  character  of  the  grapes,  or  to  the  way  in  which  they 
have  been  handled  in  the  process  of  manufacture.  For  example,  a 
wine  is  deficient  in  color:  this  may  be  due  either  to  a  lack  of  coloring 
matter  in  the  grape  or  to  an  imperfect  method  of  manufacture  which 
has  failed  to  properly  utilize  the  coloring  matter  present.  Again,  if  a 
wine  is  spoiled  by  bacterial  fermentation,  the  cause  may  lie  in  careless, 
uncleanly  methods  of  manufacture,  or  in  a  lack  of  due  acidity  in  the 
grapes,  which  favored  the  growth  of  bacteria.  In  this  way  nearly  all 
the  qualities  of  a  wine  are  influenced,  both  by  the  character  of  the  raw 
material  and  by  the  method  of  manufacture;  and  a  defect  in  either 
may  often  be  neutralized  to  a  great  extent  by  a  corresponding  change 
in  the  other. 

The  relative  importance  of  these  groups  of  factors  is  a  matter  on 
which  the  opinion  of  wine-makers  has  been  greatly  modified  during  the 
last  ten  or  fifteen  years.  Formerly,  the  first  group  was  considered  of 
overwhelming  importance  and  certain  regions  were  considered  totally 
unfit  for  the  production  of  sound  dry  wine,  on  account  of  the  supposed 
unsuitable  nature  of  the  grapes  grown  there.  Yet  many  of  these  regions 
produced  the  finest,  largest,  and  best  flavored  table  and  raisin  grapes. 
Now.  while  the  qualities  desirable  in  an  eating  grape  are  not  the  same 
as  those  necessary  for  a  wine-making  grape,  there  is  no  doubt  that  the 
main  reason  for  the  failure  to  produce  good  dry  wines  in   the  plains  of 


MANUFACTURE    OF    DRY   WINES   IN   HOT    COUNTRIES.  7 

Algeria  or  the  San  Joaquin  Valley  does  not  lie  in  the  qualities,  either 
negative  or  positive,  of  the  grapes,  but  in  the  attempt  to  make  ivines  in 
a  hot  climate  by  methods  suited  only  to  a  cool  one. 

It  is  worthy  of  note  that  in  the  regions  that  have  been  famous  for 
the  production  of  fine  wines,  such  as  Medoc,  Rheingau,  and  Burgundy, 
the  finest  and  highest-priced  wines  are  produced  on  warm,  dry  hill 
slopes,  and  in  years  when  the  summer  is  exceptionally  warm  and  dry- 
This  is  equivalent  to  saying  that  the  finest  wines  of  these  regions  are 
produced  in  situations  where  the  soil  conditions  approach  most  nearly 
to  those  of  California  vineyards,  and  in  seasons  when  the  weather  dur- 
ing the  growing  and  ripening  period  of  the  grape  approaches  most 
nearly  to  the  California  climate.  In  fact,  the  more  nearly  the  chemical 
composition  of  the  grapes  of  the  Rhine  and  the  Gironde  approaches 
that  of  California  grapes,  the  higher  the  quality  of  the  wine  and  the 
higher  the  price  it  brings  in  the  market.  Yet  it  is  perfectly  true  that 
it  is  only  exceptional  and  apparently  accidental  when  our  California 
wines  equal  or  approach  the  quality  of  the  best  wines  of  the  above 
regions. 

If  the  composition  of  the  raw  material  is  approximately  the  same,  the 
quality  of  the  manufactured  material  ought  not  to  differ  much  unless 
the  conditions  of  manufacture  are  different.  It  is  doubtless  in  the  fail- 
ure to  make  these  conditions  identical  or  equivalent  that  the  chief 
difficulty  lies.  The  use  of  the  same  methods  does  not  result  in  realizing 
the  same  conditions  in  a  hot  climate  as  in  a  cool  one,  and  whatever  the 
summer  temperature  of  the  Gironde  may  be,  the  temperature  of  the 
autumn,  when  wine-making  takes  place,  is  always  very  much  cooler 
than  it  is  here.  Many  of  the  defects  of  our  wines  which  were  supposed 
to  be  due  to  inherent  faults  of  the  grapes  have  been  shown  to  be  due  to 
bacterial  and  defective  yeast  fermentation,  and  to  be  completely  under 
the  control  of  a  suitable  method  of  wine-making.  This  does  not  mean 
that  the  locality  where  the  grapes  are  grown  is  without  influence,  or 
that  it  will  ever  be  possible  to  produce  a  Chateau  Lafitte  or  a  Schloss 
Johannisberg  in  Herault  or  Tulare.  It  does  mean,  however,  that 
wherever  grapes  mature  a  perfectly  sound  wine  of  good  quality  can  be 
made,  and  that  throughout  the  great  central  plain  of  California  sound 
dry  wines  can  be  produced  in  unlimited  quantities,  superior  in  quality  to 
the  great  bulk  of  European  wines. 

The  average  sugar-contents  of  the  grapes  of  the  plains  of  southern 
France  will  probably  not  exceed  16%,  while  that  of  the  grapes  of  the 
San  Joaquin  will  be  approximately  20%.  There  is  a  corresponding 
superiority  in  other  ingredients  such  as  body  and  tannin;  in  every- 
thing, in  fact,  except  acidity  and  perhaps  color.  The  first  of  these 
defects  can  be  remedied  legitimately  and  without  any  great  expense  arti- 
ficially, while  the  second  can  be  minimized  by  proper  methods  of  wine- 


8  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT   STATION. 

making  and  by  a  suitable  choice  of  varieties.  Taking  these  facts  into 
consideration,  then,  16  tons  of  grapes  in  the  San  Joaquin  Valley  are 
about  the  equivalent  for  wine-making  purposes  of  20  tons  in  the  plains 
of  the  Midi.  The  importance  of  this  is  proved  by  the  many  attempts 
being  made  to  increase  the  alcoholicity  of  the  wines  of  southern 
France,*  and  by  the  fact  that  the  most  effective  method  at  present 
seems  to  be  a  partial  concentration  of  the  grapes,  by  which  20%  or  30% 
of  the  water  is  evaporated  before  they  are  made  into  wine.  This  is 
equivalent  to  a  reduction  in  volume  of  20  tons  to  16  or  14  tons.  By 
this  means,  from  20  tons  of  grapes  is  made  about  2,400  gallons  of  full- 
bodied  wine,  suitable  for  export  or  blending,  having  say  12%  of  alcohol, 
instead  of  3,200  gallons  of  thin,  weak  "vin  ordinaire,"  with  only  9%  of 
alcohol.  With  a  corresponding  20  tons  of  Fresno  grapes  it  should  be 
possible  to  make,  without  the  expense  of  concentration,  3,200  gallons  of 
wine  equal  in  quality  to  the  2,400  made  from  the  same  quantity  of 
French  grapes.  That  this  has  not  been  done,  or  done  only  exceptionally 
and  accidentally,  is,  I  believe,  not  the  fault  of  the  grapes,  but  of  the 
methods  of  manufacture.  Much  of  the  dry  wine  which  it  is  attempted 
to  make  in  the  hot  interior  valleys  of  California  spoils  before  it  ever 
reaches  the  consumer,  or  more  usually  is  distilled  or  metamorphosed 
into  an  inferior  sweet  wine.  The  dry  wine  at  present  made  in  this 
region  is  to  a  great  extent  of  very  inferior  quality,  deficient  in  normal 
acidity,  tannin,  color,  aroma,  and  showing  various  defects,  cloudiness, 
acetic  and  butyric  acid,  mannite,  etc.,  due  to  bacterial  or  other  improper 
fermentations.  This  state  of  things  is  so  well  recognized  that  most 
wine-makers  of  the  San  Joaquin  Valley  have  ceased  to  attempt  to  make 
dry  wine  and  turn  all  their  grapes  into  the  sweet  wines  for  which  the 
region  is  so  specially  adapted. 

The  crisis  to  which  the  sweet-wine  market  is  subject  in  years  of 
heavy  production  would  be  modified  if  it  were  possible  to  turn  a  cer- 
tain part  of  the  grape  crop  into  dry  wine.  Many  of  the  varieties  of 
grapes  planted  in  the  great  valleys  are  moreover  more  suited  to  the 
production  of  dry  wines  than  of  sweet.  If  the  making  of  dry  wine 
is  to  pay,  however,  the  results  must  be  more  under  the  wine-maker's 
control  and  the  quality  must  be  higher  than  it  has  been  in  the  past. 

With  regard  to  the  certainty  of  control  it  is  my  firm  belief  that  there 
is  no  region  in  the  world  where  the  wine-maker  can  be  so  sure  of  making 
every  year  a  good,  sound,  dry  wine  of  uniform  quality  as  in  the  great 
central  plain  of  California.  An  opinion  so  opposed  to  the  practical 
results  of  the  past  was  not  arrived  at  without  careful  consideration, 
and  is  based  principally  upon  the  methods  and  tendencies  of  modern 

*  "  What  we  need  to  satisfy  our  markets  is  alcoholic,  heavy-bodied,  deeply  colored 
wines  such  :is  are  not  produced  by  our  modern  methods  of  intensive  cultivation." 
"  La  Concentration  des  Vins,"  by  L.  Roos,  Bordeaux,  1902. 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES.  9 

wine-making  in  Algeria  and  southern  France  and  on  the  long  and  care- 
ful tests  conducted  for  many  years  by  the  Agricultural  Experiment 
Station  of  the  University  of  California  at  the  Fresno,  Tulare,  Amador,  and 
San  Luis  Obispo  substations  and  the  viticultural  cellar  and  labora- 
tories at  Berkeley.  To  attain  this  desired  result,  however,  requires  very 
considerable  changes  in  the  present  methods  of  wine-making,  and  in 
the  course  of  this  report  an  attempt  will  be  made  to  show  the  essential 
features  of  this  necessary  change. 

The  conditions  upon  which  the  quality  of  wine  depend  are: 

First — Those  which  affect  the  nature  of  the  raw  material,  viz. :  variety 
of  grape,  climate,  soil,  methods  of  cultivation  (including  pruning, 
fertilizing,  etc.),  vine  diseases,  time  of  gathering. 

Second — Those  which  depend  on  the  methods  of  manufacture.  These 
methods  may  affect  the  wine  in  a  great  variety  of  ways.  They  may 
modify  its  composition  by  means  of  the  addition  of  various  substances 
which  occur  naturally  in  the  grape,  such  as  sugar,  water,  tartaric  acid, 
and  tannin,  or  even  of  substances  which  do  not  occur  there  in  appre- 
ciable quantities  naturally,  such  as  citric  acid  and  plaster.  They  may 
cause  a  more  or  less  perfect  utilization  of  the  substances  in  the  grape, 
and  in  this  way  control  to  a  great  extent  the  amount  of  color  and 
tannin,  and  even  of  alcohol  and  acid  in  the  resulting  wine. 

It  is  in  the  control  of  the  fermentation,  however,  that  the  methods  of 
manufacture  have  the  most  scope  for  affecting  the  quality  of  the  wine 
for  good  or  ill.  The  character  of  the  fermentation  depends  on  four 
main  factors:  (a)  the  composition  of  the  grape;  (b)  the  kind  and  num- 
ber of  micro-organisms  (yeasts,  molds,  and  bacteria)  present;  (c)  the 
temperature  of  the  fermenting  mass;  and  (d)  the  amount  of  aeration. 

In  accordance  with  these  facts,  the  attempts  at  finding  a  solution  to 
the  problem  of  the  manufacture  of  sound,  dry  wine  of  good  quality  in 
hot  climates  have  been  made  along  different  lines,  which  are  discussed 
in  the  remaining  portion  of  this  bulletin. 


10  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT   STATION. 


METHODS  FOR  IMPROVING  MANUFACTURE  OF  DRY  WINES  IN  HOT 

CLIMATES. 

A.  Amelioration  of  the  character  of  the  raw  material. 

1.  Suitable  varieties  of  grapes. 

2.  Appropriate  methods  of  cultivation. 

3.  Time  of  gathering  grapes. 

4.  More  complete  utilization  of  the  substances  in  the  grapes. 

5.  Addition  of  substances  deficient  in  the  grapes. 

6.  Addition  of  substances  not  found  normally  in  the  grapes. 

B.  Control  of  fermentation. 

(I)  By  modifying  the  temperature. 

1.  Cooling  devices  (physical). 

2.  Cooling  devices  (chemical). 

3.  Postponement  of  fermentation  until  winter. 

4.  Fermentation  in  a  cool  locality. 
(a)  Transportation  of  grapes. 

b)  Transportation  of  crushed  grapes  or  must, 

(c)  Concentration  of  grapes  for  transportation. 

(d)  Drying  grapes  for  transportation. 

(II)  By  controlling  the  kind  of  fermentative  agents  present, 

1.  Sterilization  (physical). 

2.  Sterilization  (chemical). 

3.  Pure  and  selected  yeasts. 

AMELIORATION  OF  THE  CHARACTER  OF  THE  RAW  MATERIAL. 

VARIETIES    OF    GRAPES. 

The  proper  choice  of  varieties  of  grapes  to  plant  is  the  first  essential 
in  the  production  of  good  dry  wine  in  any  climate,  and  is  especially 
necessary  in  one  which  is  either  cooler  or  hotter  than  the  normal  for 
the  growth  of  the  vine.  A  variety  which  gives  excellent  results  in  one 
climate  is  often  quite  useless  in  another.  The  grapes  of  Roussillon  will 
not  ripen  on  the  Rhine,  and  those  of  Burgundy  will  not  bear  paying 
crops  in  Fresno.  The  Cabernet  Sauvignon,  the  grape  from  which  the 
bulk  of  the  Chateau  wines  of  the  Medoc  is  made,  the  highest-priced  red 
wines  made  anywhere,  is  said  to  produce  an  undrinkable  wine  in  Algeria. 

For  this  reason  nothing  very  certain  can  be  gathered  regarding  vari- 
eties suitable  for  our  hotter  regions  by  noting  which  are  planted  in 
other  countries.  Luckily,  the  long  and  complete  series  of  variety  tests 
which  the  Agricultural  College  at  Berkeley  has  made  during  the  last 
twenty  years  has  solved  this  question  very  satisfactorily  for  most  parts 
of  California,  especially  as  to  what  varieties  are  most  suitable  for  red 
wine.  A  short  summary  of  these  results  was  published  in  the  Report 
of  the  College  of  Agriculture  in  1898,*  and  it  is  interesting  to  see  how 
far  they  correspond  with  the  experience  and  practice  of  southern  French 
and  more  particularly  of  Algerian  growers. 

*  Partial  report  of  Work  of  the  Agricultural  Experiment  Station  of  the  University  of 
California.    Art.,  "  Memoranda  on  Wine,  Table,  and  Raisin  Grapes,"  pp.  245-253. 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES.  11 

In  the  south  of  France  very  few  varieties  are  planted  on  a  large  scale, 
and  the  great  bulk  of  the  vineyards  consists  of  Aramon.  This  is  the 
ideal  grape  for  quantity,  producing  an  abundance  of  thin  watery  wine 
with  good  acidity  and,  though  deficient  in  alcohol,  color,  body,  and 
flavor,  without  any  positive  defects  and  capable  of  improvement  by 
blending  with  suitable  heavy  wines  such  as  those  from  parts  of  Algeria. 
During  the  last  few  years  of  heavy  production  and  increasing  competi- 
tion with  "sugar  wines"  and  with  similar  but  superior  wines  from  the 
rich  plains  of  Algeria,  the  Aramon  has  been  much  less  profitable,  and 
there  is  a  tendency  now  to  plant  grapes  yielding  a  less  watery  product. 
The  principal  of  these  are  the  Grand  Noir  (a  kind  of  Bouschet),  the 
Petit  Bouschet,  and  the  Carignane.  The  last  would  be  planted  more 
but  for  its  susceptibility  to  fungous  diseases.  In  higher  and  well- 
drained  land  the  Alicante  Bouschet,  which  is  recognized  as  the  best  of 
the  Bouschets,  is  planted,  but  on  lower  and  richer  soil  it  is  found 
extremely  difficult  to  defend  it  from  oidium  and  other  fungous  parasites. 
A  few  Matarb,  Mourastel,  and  Cinsaut  are  found,  but  not  in  large 
quantities.  For  white  wine  the  Aramon  is  used  principally,  together 
with  the  Piquepoule  and  the  Terret. 

In  Algeria  at  the  present  time  hardly  anything  is  planted  except  the 
Carignane  and  Alicante  Bouschet,  which  unite  there,  better  than  any 
other  varieties,  productiveness  with  fair  quality.  Their  susceptibility 
to  disease  is  more  easily  controlled  in  the  drier  climate  of  Algeria,  but 
they  still  require  a  certain  amount  of  spraying.  Other  varieties  grown 
there,  to  some  extent,  are  Cinsaut,  Aramon,  Mourastel,  and  Grenache 
for  red,  and  Farana  for  white  wine.  These,  especially  the  first  two,  do 
not  give  thorough  satisfaction,  on  account  of  their  lack  of  the  color,  body, 
and  alcohol  which  constitute  the  main  value  of  Algerian  wines.  In  the 
higher  regions,  especially  in  the  neighborhood  of  Miliaria,  where  the 
best  wines  of  the  country  are  produced,  a  certain  amount  of  Pinot  and 
Gamai  vines  are  grown;  but  these  are  gradually  giving  way  to  the 
Carignane,  which  produces  much  more  abundantly.  Very  little  seems 
to  have  been  done  in  experimenting  with  varieties  other  than  those  of 
France.  The  vines  of  Burgundy  and  the  Medoc  have  generally  failed 
to  give  the  desired  results  in  either  quality  or  quantity,  and  the  varie- 
ties adopted  are  those  among  the  southern  French  grapes  which  suit 
the  conditions  best. 

In  the  report  of  the  Agricultural  Experiment  Station  referred  to 
above,  the  varieties  recommended  for  the  production  of  dry  red  wine  in 
the  hotter  parts  of  the  San  Joaquin  Valley  are  Alicante  Bouschet,* 
Valdepefias,  St.  Macaire,  Lagrein,  Refosco,  Barbera;  and  for  the  foot- 

*  This  variety  and  the  Petit  Bouschet  were  distributed  over  California  with  exchanged 
labels,  and  in  this  way  became  interchanged  at  the  Experiment  Stations.  The  remarks 
in  older  reports,  including  the  one  referred  to,  regarding  "  Petit  Bouschet,"  apply  there- 
fore to  Alicante  Bouschet. 


12  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 

hills  of  the  Sierra,  Alicante  Bouschet,  Aramon,  and  Serine.  There 
seems  no  occasion  at  present  to  modify  these  recommendations,  and  it  is 
extremely  desirable,  if  dry  red  wines  are  to  be  made  in  those  regions,  that 
larger  quantities  of  these  varieties,  especially  of  the  first  two,  should  be 
planted  instead  of  so  much  Carignane,  Matarb,  and  Zinfandel,  which 
give  much  inferior  results  there,  so  far  as  regards  quality,  without  a 
sufficiently  great  compensation  as  regards  quantity.  For  dry  white 
wine,  the  varieties  recommended  were  Burger,  Folle  blanche,  Aramon, 
for  the  valley,  and  possibly  Clairette  for  the  foothills;  but  it  is  doubtful 
if  at  present  it  is  advisable  to  plant  grapes  for  dry  white  wine  in  those 
localities.  That  throughout  the  valley,  dry  red  wines  of  quality  equal 
at  least  to  those  of  the  plain  of  the  Metidja  in  Algeria  can  be  produced 
there  can  be  little  doubt,  if  a  certain  proportion  of  Valdepefias  or  any  of 
the  other  varieties  recommended  are  grown  to  bring  up  the  color,  acid, 
extract,  and  aroma  of  the  varieties  already  planted,  and  if  a  system  of 
wine-making  is  adopted  which  will  utilize  the  good  qualities  of  the 
grapes  and  neutralize  the  injurious  effects  of  the  high  temperature  of 
the  vintage  season. 

TIME    OF    GATHERING    THE    GRAPES. 

The  stage  of  ripeness  at  which  the  grapes  are  gathered  has  great  influ- 
ence on  the  character  of  the  fermentation  and  the  quality  of  the  resulting 
wine.  Within  certain  limits  the  less  mature  the  grapes,  the  more  acid 
and  the  less  sugar  will  they  contain,  and  the  easier  and  more  complete 
will  be  the  fermentation.  For  this  reason  the  premature  gathering  of 
the  crop  has  been  suggested  and  practiced  as  a  means  of  avoiding  dif- 
ficult fermentations  in  hot  regions.  So  far  as  the  avoidance  of  "  stuck" 
wines  is  concerned  the  method  is  usually  successful;  but  there  is  loss 
in  both  quantity  and  quality,  which  in  many  cases  more  than  counter- 
balances the  gain. 

With  regard  to  the  quality  of  the  wine,  it  is  well  known  that  the 
best  wine  can  be  made  only  from  grapes  which  have  reached  the  stage 
of  maturity  which  is  known  as  "  wine-making  ripeness."  Before  that 
stage  is  reached  the  grapes  not  only  contain  substances  which  give  a 
disagreeable  harshness  to  the  wine,  but  have  failed  to  elaborate  those 
other  substances  to  which  the  finer  flavors  and  aromas  of  good  wine  are 
due.  To  a  certain  extent,  this  stage  of  ripeness  is  independent  of  the 
degrees  of  sugar  or  acidity  present,  and  can  only  approximately  be  deter- 
mined by  means  of  the  mustimeter  and  acid  test,  or  other  analytical 
means  alone.  While  an  Aramon  in  the  south  of  France  may  have 
attained  its  optimum  degree  of  maturity  for  wine-making  purposes  when 
it  contains  16%  of  sugar,  a  Matarb  in  the  Sacramento  Valley  may  be  still 
far  from  ripe  enough  for  the  same  purposes  when  it  contains  20%  of 
sugar. 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES.  13 

We  can  not,  therefore,  gather  our  grapes  prematurely  without  some 
sacrifice  of  quality,  and  it  is  only  in  the  absence  of  better  means  of 
controlling  the  fermentation  that  it  can  be  recommended.  This  loss 
of  quality  can  be  minimized  in  many  cases,  however,  while  still  retain- 
ing the  advantages.  If  instead  of  gathering  all  the  grapes  when  they 
are  imperfectly  mature,  we  allow  the  main  part  of  the  crop  to  reach 
"wine-making  ripeness"  and  then  crush  them  with  a  suitable  propor- 
tion of  very  unripe  grapes  to  enhance  the  acidity,  we  improve  the  fer- 
mentation with  less  detriment  to  the  quality.  The  ripe  grapes  contain 
those  substances  necessary  for  the  quality  of  the  wine,  and  the  unripe 
those  necessary  for  a  good  fermentation.  This  can  be  done  only  when 
the  ripe  and  the  unripe  grapes  can  be  obtained  at  the  same  time,  for  it 
is  essential  that  they  should  be  crushed  and  fermented  together.  The 
two  kinds  of  grapes  may  be  of  different  varieties,  ripening  at  different 
epochs,  or  of  the  same  variety,  from  early  and  late  locations  or  localities. 
One  of  the  best  methods  of  applying  this  remedy  is  to  use  the  bunches 
of  second  crop  on  the  same  vines.  When  the  first  crop  has  reached  its 
optimum  degree  of  ripeness,  the  second  crop  of  most  varieties  is  just  in 
the  right  condition  to  correct  the  lack  of  acidity  in  the  first.  This 
practice  is  largely  employed  in  parts  of  Algeria,  and  also  in  South 
Africa,  with  great  success.  The  resulting  wines,  while  showing  a  slight 
"greenness"  to  the  palate,  are  much  superior  in  quality  to  those  made 
altogether  from  grapes  gathered  prematurely,  while  fermenting  with 
equal  ease  and  completeness. 

With  regard  to  the  loss  in  quantity  some  interesting  conclusions  may  be 
drawn  from  some  recent  French  investigations.*  These  show  an  average 
increase  of  volume  in  grapes  of  2%  per  day  during  the  two  or  three 
weeks  preceding  maturity,  and  an  increase  of  .7%  per  day  of  the  sugar 
during  the  same  period.  The  actual  figures  noted  vary  within  very  wide 
limits  with  different  varieties  of  grapes  and  different  localities,  but  the 
average  of  all  the  results  will  doubtless  give  us  an  approximation  to  the 
average  in  practice.  If,  then,  we  gather  the  grapes  before  they  attain 
the  proper  degree  of  maturity,  we  obtain  a  smaller  quantity  of  wine  of 
a  lower  degree  of  alcohol.  This  loss  may  be  considered  as  the  cost  of 
the  acid  in  the  partially  ripe  grapes,  to  which  the  better  fermentation 
is  due.  If  we  compare  this  cost  with  that  of  a  sufficient  amount  of  tar- 
taric or  citric  acid  to  attain  the  same  result,  we  will  find  it  much  higher. 
An  example  will  make  this  clearer.  If  we  have  a  vineyard  where  the 
grapes  at  maturity  contain  22%  of  sugar  and  .4%  of  acidity,  we  might, 
by  picking  them  a  week  before  maturity,  have  sufficient  acidity  to  insure 
a  thorough  fermentation.  At  this  time  (using  the  figures  given  above) 
the  grapes  would  contain  about  16.9%  of  sugar  and  ,6%  of  acidity,  and 

*Aime  Girard  et  L.  Lindet :     "  Recherches  sur  le  developpement  progressif  de  la  grappe 
de  raisin."     Paris,  1898. 


14  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 

the  quantity  of  bunches  that  at  maturity  would  weigh  2,000  pounds 
would  at  this  time  weigh  only  1,780  pounds.  The  cost,  then,  of  the 
extra  .2%  of  acidity  that  we  would  obtain  may  be  reckoned  as  follows: 

220  pounds  of  grapes,  at  $15 $1  65 

90  pounds  of  sugar,  at  3  cents 2  70 

Total  cost  of  acidity  per  ton  of  grapes $4  35 

Reckoning  the  price  of  tartaric  acid  at  25  cents  per  pound,  the  cost 
of  this  .2%  of  acidity  would  be  only  $1;  and  if  citric  acid  were  used, 
the  practically  equivalent  amount  would  cost  even  less.  These  figures 
are  merely  approximate,  and  the  difference  in  cost  may  often  be  less 
than  this;  but  it  is  just  as  likely  to  be  more. 

If,  then,  we  consider  the  losses  in  both  quality  and  quantity,  it  is 
rarely  if  ever  advisable  to  pick  grapes  prematurely  for  the  purpose  of 
promoting  a  good  fermentation;  cheaper  and  better  methods  are  usually 
available.  The  principal  exception  is  when  a  second  crop  is  available 
in  the  right  condition  when  the  first  crop  is  being  picked,  especially 
when  this  second  crop  is  of  a  variety  which  can  not  be  depended  on  in 
the  locality  to  attain  full  ripeness  later. 

Another  point  of  practical  importance  regarding  the  time  of  gathering- 
is  worthy  of  notice.  In  large  vineyards  of  one  variety  of  grape  or  of 
several  ripening  at  about  the  same  time,  it  is  impossible  to  gather  all  the 
grapes  just  at  the  most  desirable  stage  of  maturity.  For  this  reason  it 
is  usually  necessary  to  commence  gathering  before  the  grapes  have 
quite  reached  this  stage,  and  to  continue  after  they  have  passed  it.  In 
Algeria  it  is  usual  to  commence  the  vintage  as  soon  as  the  grapes  are 
capable  of  producing  wine  of  8%  of  alcohol,  and  before  the  vintage  is 
over  they  are  usually  sweet  enough  to  produce  wine  of  12%  to  14%  of 
alcohol.  If  all  the  fermentations  are  complete  a  good  average  wine  is 
made  by  blending  all  together.  The  high  acidity  of  the  early-gathered 
grapes  supplements  the  low  acidity  of  the  late-gathered  grapes.  Too 
much  acidity  in  the  must  is  a  much  less  serious  defect  than  too  little,  as 
much  is  deposited  during  fermentation,  and  more  during  the  first  few 
weeks  following.  The  cause  of  this  is  the  presence  of  alcohol  and  the 
fall  of  temperature,  both  of  which  conditions  make  the  wine  less  capable 
of  holding  the  acid  tartrates  in  solution.  For  this  reason,  when  the 
wine  made  toward  the  end  of  the  season  is  deficient  in  acid  it  is  desirable 
to  blend  it  with  the  early-made  acid  wine  as  soon  as  possible,  before  the 
latter  has  deposited  too  much  of  its  acidity.  Some  wine-makers  in  fact 
mix  the  early-fermented  wine  with  the  over-ripe  grapes  when  they  are 
crushed  or  when  they  have  half  fermented.  This  utilizes  the  surplus 
acidity  most  effectually,  and  at  the  same  time  aids  fermentation  by 
diluting  the  sugar  and  cooling  the  temperature  of  the  later  fermenta- 
tions. The  method  has  the  defect,  however,  of  entailing  a,  double 
handling  of  a  part    of  the  wine,  and   exposing  a  wine  which    is   already 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES.  15 

made  and  sound  to  the  risks  of  a  second  fermentation  under  less  favor- 
able conditions  than  the  first. 

METHODS    OF    CULTIVATION. 

The  composition  of  the  grapes,  as  well  as  the  amount  of  the  crop,  can 
be  modified  very  considerably  by  the  system  of  pruning,  tillage,  irriga- 
tion, and  manuring  adopted.  The  old  idea  that  the  smaller  the  crop 
the  higher  the  quality  of  the  wine  is  by  no  means  always  or  even  gen- 
erally true.  Anything  which  weakens  the  vine  beyond  a  certain  limit 
will  decrease  its  bearing  capacity,  and  at  the  same  time  injure  the  quality 
of  the  grapes.  Vines  weakened  by  disease,  soil  exhaustion,  or  lack  of  soil 
moisture  produce  badly  ripened  grapes,  deficient  in  sugar,  acid,  and 
other  elements  which  are  necessary  for  the  production  of  good  wine. 
This  is  especially  true  of  any  condition  which  prevents  an  abundant 
growth  of  healthy  leaves  throughout  the  season.  When  the  leaves  cease 
to  perform  their  functions  properly,  the  grapes  cease  to  develop.  For 
this  reason  it  is  often  possible,  by  appropriate  cultural  methods,  to 
increase  the  quantity  of  the  crop,  and  at  the  same  time  to  ameliorate 
its  quality.  Anything  which  increases  the  size  of  the  bunches  and 
berries  without  interfering  with  their  normal  ripening  usually  improves 
their  quality.  This  is  particularly  true  in  hot  climates,  where  there  is 
ordinarily  no  lack  of  sugar  in  the  grapes  or  where  there  is  often  too 
much. 

On  the  other  hand,  anything  which  increases  the  number  of  bunches 
at  the  expense  of  the  proper  development  of  the  individual  berries 
usually  produces  a  deterioration  in  the  quality;  and  often  the  increase 
in  quantity  is  more  apparent  than  real,  as  small,  badly  developed  grapes 
yield  comparatively  little  wine. 

Pruning. — The  larger  and  more  vigorous  a  vine,  the  more  grapes  it  is 
capable  of  bringing  to  perfection.  The  more  buds  one  leaves  on  a  vine 
in  pruning,  the  more  bunches  it  is  enabled  to  produce.  Our  pruning 
should  be  so  calculated,  therefore,  as  to  give  the  vine  the  opportunity  to 
produce  as  many  bunches  as  it  can  properly  support  and  bring  to  the 
desired  degree  of  maturity.  A  vine  pruned  too  long  or  given  too  many 
spurs  may  yield  a  large  number  of  bunches,  but  the  grapes  will  be 
deficient  in  juice,  sugar,  acid,  and  all  the  constituents  essential  for  good 
wine.  Increasing  the  amount  of  bearing  wood  on  a  vine  will  increase 
the  crop  only  within  certain  limits.  To  pass  these  limits  we  must 
strengthen  the  vine  by  improved  tillage,  irrigation,  and  fertilization. 
An  essential  condition  of  both  good  crops  and  good  wine  is  a  strong 
healthy  vine. 

Irrigation. — It  was  long  believed  that  it  was  impossible  to  make 
good  wine  from  irrigated  vineyards.     But  this  is  no  more  true  than  the 


16  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

equally  widespread  belief  that  irrigation  is  incompatible  with  the  pro- 
duction of  other  good  fruit.  Irrigation  properly  applied  is  in  fact  one  of 
the  surest  means  of  insuring  both  the  quantity  and  quality  of  the  crop, 
as  it  gives  the  vine  the  amount  of  water  it  needs  at  the  time  it  needs  it. 
It  frequently  occurs  during  the  latter  part  of  dry  seasons,  especially  with 
late  ripening  varieties  such  as  Matarb,  that  the  grapes  suddenly  cease  to 
develop  either  in  size  or  sugar,  in  spite  of  the  warm  weather.  This  is 
because  the  vegetation  of  the  vine  is  arrested  and  the  leaves  and  roots 
fail  to  perform  their  functions  properly.  Grapes  grown  on  a  dry 
hillside  may,  under  such  conditions,  fail  to  develop  more  than  16%  of 
sugar,  while  the  same  variety  in  a  moister  soil  with  the  same  weather 
conditions  may  reach  20%.  Under  such  conditions  irrigation,  when 
practicable,  will  remedy  the  trouble.  Irrigation  may  also  be  used  to 
remedy  the  opposite  condition,  viz.:  the  development  of  too  much  sugar 
in  the  grapes.  Many  convincing  tests  of  summer  irrigation  of  vines 
have  lately  been  made  in  southern  France.  Those  of  A.  Muntz*  are 
particularly  suggestive  to  Californians,  as  they  were  made  in  the  Rous- 
sillon,  where  the  climate  resembles  more  nearly  that  of  California  than 
in  any  other  part  of  France.  In  a  series  of  twelve  tests  made  with 
Aramon  and  Carignane  vines,  late  summer  irrigation  increased  the 
weight  of  grapes  produced  29%,  and  the  weight  of  sugar  per  acre  20%. 
The  average  composition  of  the  grapes  from  irrigated  and  from  non- 
irrigated  vines  was  as  follows: 

Sugar.  Acid. 

Irrigated 18.8%  1.11% 

Non-irrigated 19.6%  .96% 

The  wine  made  from  the  irrigated  grapes  contained  11%  of  alcohol, 
and  that  from  the  others  11.5%,  but  otherwise  the  quality  was  identical. 
Calculating  the  value  of  the  crop  of  wine  at  2  francs  per  degree  per 
hectoliter — the  market  price  at  the  time  of  the  test,  corresponding  to 
17^  cents  per  gallon  for  wine  of  11%  alcohol — the  gain  per  acre  due  to 
the  irrigation  was  $20.  There  can  be  no  doubt  that  in  many  cases  the 
gain  in  California  from  irrigation  properly  applied  would  be  propor- 
tionately greater  where  the  grapes  tend  to  produce  too  much  sugar  and 
too  little  acid  for  proper  fermentation.  In  many  vineyards  in  the  irri- 
gated portions  of  California  undoubtedly  as  much  water  as  the  vines 
can  profitably  use  is  applied,  and  in  some  cases  more;  but  no  fear  need 
be  entertained  that  irrigation  will  depreciate  the  quality  of  the  wine  if 
it  does  not  decrease  the  sugar-contents  of  the  grapes  below  19%  (about 
20.2%,  Balling).     There  is  far  more  danger  that  insufficient  irrigation 

*  "  De  reflect  des  Arrosages  Tardifs."  A.  Muntz,  in  "Revue  de  Viticulture,"  vol. 
11,  p.  541. 

*  M.  G.  BrSmond  more  than  doubled  his  crop  by  judicious  irrigation,  at  the  same 
time  improving  the  quality  and  alcoholicity  of  his  wine.  "  Progres  Agricoleet  Viticole," 
vol.  dZt  p.  897. 


MANUFACTURE   OF    DRY   WINES   IN   HOT    COUNTRIES.  17 

in  the  hot  interior  valleys  will  result  in  grapes  deficient  in  acid  and 
with  excessive  sugar,  giving  unsound  and  inferior  wines. 

The  time  of  irrigation  is  of  equal  importance  with  the  amount.  It  is 
very  important  that  the  vine  should  have  sufficient  moisture  available 
during  the  period  between  what  the  French  grape-growers  call  the 
"  Veraison  " — (the  time  when  the  grapes,  having  attained  almost  their 
full  size,  commence  to  color) — and  full  ripeness.  During  this  period 
there  is  a  migration  toward  the  fruit  of  materials  accumulated  in  vari- 
ous parts  of  the  vine,  and  great  changes  take  place  in  the  composition  of 
the  grapes.  Growth  relaxes  in  the  leaves  and  shoots,  which  become  paler. 
It  is  a  critical  period  in  the  maturing  of  the  crop,  and  if  the  vine  is 
not  well  nourished  and  supplied  with  water  it  is  not  able  to  supply  the 
energy  necessary  for  the  profound  chemical  and  physical  changes  taking 
place  in  the  fruit.*  During  the  latter  part  of  this  period,  which  lasts  for 
from  four  to  six  weeks,  it  is  very  important  that  the  vine  should  not 
receive  a  check  from  lack  of  available  moisture.  It  is  often  observed 
in  France  and  Algeria  that  when  the  autumn  is  hot  and  dry,  the  devel- 
opment of  the  grapes  is  arrested  and  the  crop  is  deficient  not  only  in 
quantity  but  often  in  sugar  and  acid.  This  explains  the  good  effects 
of  late  irrigation,  which  Muntz  in  Roussillon  (already  quoted)  and 
others  in  southern  France  have  found  so  noticeable. 

Fertilization. — With  regard  to  the  effect  of  fertilization  on  the  quality 
of  the  grapes,  the  same  line  of  reasoning  applies  as  with  irrigation.  A 
starved  vine  will  produce  not  only  few  grapes  but  inferior  grapes,  and 
a  fertilizer  which  will  increase  the  crop  will  usually  improve  its  quality; 
and  no  deterioration  of  quality  from  this  source  need  be  feared  so  long 
as  the  sugar-content  of  the  grapes  remains  sufficiently  high.  Fertiliza- 
tion of  the  vines  is  carried  out  very  thoroughly  and  regularly  in  southern 
France,  and  the  best  practice  is  considered  to  be  an  annual  treatment. 
The  crop  is  very  much  increased  by  this  means,  often  doubled  without 
sacrifice  of  quality,  f 

MORE    COMPLETE    UTILIZATION    OF    THE    SUBSTANCES    IN    THE    GRAPES. 

Some  of  the  defects  of  the  wines  of  hot  countries  may  be  attributed, 
not  so  much  to  deficiencies  in  the  grapes,  as  to  the  failure  to  properly 
utilize  the  materials  present.  The  fermentation  of  red  grapes  with  the 
stems  has  been  advocated  as  a  means  of  increasing  the  body,  acidity, 
and  tannin-contents  of  the  wine.  In  the  south  of  France  this  is  the 
common  practice.  The  observed  good  effect  is  due,  however,  not  to  the 
materials  in  the  stems,  but  to  those  in  the  skins,  which  the  presence  of 
the  stems  permits  to  be  more  thoroughly  extracted.  The  good  effects 
of  fermenting  with  the  stems,  then,  are  mainly  indirect,  and  may  be 

*  G.  Foix:  "  Cours  Complet  de  Viticulture,"  p.  267. 
t  Degrully:  "  Progres  Agricole  et  Viticole,"  vol.  32,  p.  669. 
2  —  BUL,  167 


18  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 

obtained  by  any  means  which  promotes  the  extraction  of  matters  from 
the  skins,  such  as  stirring,  long  maceration,  etc.  On  the  other  hand, 
the  direct  effect  of  the  stems  is  to  give  a  harshness  to  the  wine  which  is 
incompatible  with  the  best  quality,  and  the  practice  is  advisable,  there- 
fore, only  where  very  common  wines  are  made.  In  Algeria  the  stems 
are  usually  rejected,  and  the  extraction  of  color  and  tannin  from 
the  skins  is  promoted  by  pumping-over  during  the  last  stages  of  fer- 
mentation. 

In  Algeria  the  use  of  cooling  machines  to  moderate  the  heat  of  fer- 
mentation, while  almost  completely  successful  in  its  object  of  enabling 
the  cellarman  to  be  sure  of  producing  a  sound  dry  wine,  has  brought  a 
very  serious  trouble  in  its  train.  The  main  value  of  Algerian  wines, 
the  special  character  which  made  them  desirable  to  the  wine  merchants 
of  France,  was  their  heavy  body,  high  astringency,  and  deep  color. 
These  three  important  qualities  have  all  been  modified  by  the  cool  fer- 
mentations now  practiced.  Wines  which  are  not  allowed  to  exceed  90° 
or  93°  F.  during  fermentation,  though  they  are  usually  sound  and  dry, 
and  free  from  those  defects  and  diseases  which  used  to  characterize  so 
many  Algerian  wines,  possess  much  less  body,  color,  and  tannin  than 
the  wines  made  by  the  old  method.  The  gain,  therefore,  of  greater  cer- 
tainty in  results  and  less  spoiled  wine  is  to  a  great  extent  offset  by  the 
loss  of  much  of  the  character  which  constituted  the  value  of  the  old 
wines  when  they  were  successfully  made.  It  is  beginning  to  be  realized 
now  that  too  much  emphasis  has  been  placed  on  the  ill  effects  of  high 
temperature  in  fermenting  red  wine,  and  the  good  effects  of  those  tem- 
peratures lost  sight  of.  Attempts  have  therefore  been  made  lately  to 
devise  a  system  of  wine-making  which  will  combine  the  good  effects  of 
high  temperatures  in  the  complete  extraction  of  the  grapes,  and  the  good 
effects  of  low  temperatures  in  the  complete  fermentation  of  the  wine 
and  the  absence  of  injurious  ferments. 

The  most  notable  system  of  this  kind,  and  the  only  one  in  practical 
use  in  Algeria,  is  that  of  M.  Debono,  a  large  wine-maker  of  Boufarik. 
The  results  of  the  method  were  kindly  shown  at  the  cellar  of  M.  Duroux 
at  Rouiba,  where  200,000  gallons  of  wine  were  made  by  this  method 
last  year.  The  wine,  as  seen  in  December,  1904,  two  months  after 
the  vintage,  was  clear,  dry  and  sound,  and  superior  in  color,  body,  and 
taste  to  that  of  any  other  large  cellar  tasted  in  Algeria.  The  method 
in  brief  is  as  follows: 

1.  The  grapes  are  crushed  and  stemmed  into  amphoras*  of  11,000 
gallons  capacity,  with  strainers  at  the  bottom. 

2.  The  must  is  then  drawn  off.  This  is  done  preferably  immediately 
after  crushing,  but  in  practice  often  after  fermentation  is  half  over. 

*The  amphoras  used  in  Algeria  for  fermenting  and  storing  wine  arc  vats  shaped  like 
huge  bottles,  and  constructed  of  concrete,  masonry  or  brick,  and  lined  with  glass. 


MANUFACTURE    OF    DRY   WINES    IN    HOT    COUNTRIES.  19 

3.  This  must  is  pumped  into  amphoras  of  12,500  gallons  capacity, 
treated  with  sulfite  to  moderate  the  temperature,  and  allowed  to  fer- 
ment until  all  but  about  2%  of  the  sugar  has  disappeared. 

4.  As  soon  as  the  must  contains  only  2%  of  sugar  it  is  pumped  back 
on  to  the  pomace  in  the  original  amphora. 

5.  The  pomace  in  this  amphora  has  meanwhile  become  very  hot — 
44°-45c  C.  (111°-113°  F.). 

6.  The  must  is  now  pumped  over  the  hot  pomace  repeatedly  until  it 
has  extracted  sufficient  color  and  tannin,  and  is  then  pumped  back  into 
the  12,500-gallon  amphoras,  where  fermentation  is  completed.  Usually 
the  wine  is  quite  dry  by  the  time  it  arrives  in  the  larger  amphoras  the 
second  time. 

The  time  of  the  operation  from  the  crushing  of  the  grapes  until  the 
wine  is  placed  in  the  final  amphoras  is  usually  about  four  days.  The 
method  requires  constant  vigilance  day  and  night. 

The  must  should  not  be  allowed  to  become  quite  dry  before  being 
pumped  over  the  pomace,  or  the  wine  will  be  inferior  in  color  and 
quality.  On  the  other  hand,  it  must  not  be  pumped  over  with  more 
than  4%  of  sugar,  or  there  is  danger  of  a  hot  fermentation  and  its 
accompanying  effects. 

By  this  method  we  get  the  good  effects  of  hot  temperature  in  the 
pomace  vat,  where  it  macerates  the  skins  and  so  enables  the  must  to 
extract  the  color,  body,  and  tannin.  At  the  same  time  we  get  the  good 
effects  of  low  temperature  in  the  must  vats,  where  the  wine  becomes 
dry  and  acquires  the  bouquet  characteristic  of  cool  fermentations.  The 
reason  we  do  not  get  the  bacterial  fermentations  usually  accompany- 
ing hot  fermentations  is  probably  because  the  great  bulk  of  the  wine 
never  becomes  hot,  and  the  yeast  remains  strong  and  healthy  and 
thoroughly  defecates  the  wine  before  the  bacteria  have  an  opportunity 
to  injure  it.  In  an  ordinary  hot  fermentation  the  weakening  of  the 
yeast  has  probably  more  to  do  with  the  growth  of  bacteria  than  the 
favorable  influence  of  the  high  temperature.  There  is  undoubtedly 
some  loss  of  alcohol  in  the  pomace  vats,  due  to  the  very  high  tempera- 
ture, but  this  is  apparently  more  than  offset  by  the  gain  in  alcohol  in 
the  cool  must  vats.  I  was  assured  that  the  wines  fermented  in  this 
way  usually  showed  a  higher  degree  of  alcohol  than  those  fermented 
in  the  ordinary  way. 

Effects  of  High  Temperatures. — The  effects  of  various  degrees  of  tem- 
perature in  the  process  of  wine-making  are  of  two  kinds,  which  should 
be  carefully  distinguished.  They  are:  (1)  Those  which  are  due  directly 
to  the  degree  of  temperature  and  its  immediate  action  on  the  must  or 
wine;  and  (2)  those  which  are  due  indirectly  to  the  degree  of  tempera- 
ture through  its  modifying  influence  on  the  character  and  kind  of  the 
micro-organisms  present.     It  is,  to  a  great  extent,  to  a  failure  to  prop- 


20  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

erly  recognize  this  distinction  that  so  much  difference  of  opinion  exists 
as  to  the  most  favorable  temperature  for  fermentation,  and  as  to  the 
advisability  of  pasteurizing  must  or  wine. 

Under  the  ordinary  conditions  of  wine-making;  the  second  of  these 
groups  of  effects  is  by  far  the  more  important.  That  is,  the  great  differ- 
ences found  in  wines  fermented  at  different  temperatures  between  the 
extremes  of  20°  C.  (68°  F.)  and  40°  C.  (104°  F.)  are  due  principally  to 
the  differences  caused  in  the  kinds  and  proportions  of  the  various  molds, 
yeasts,  and  bacteria  present,  and  to  the  different  physiological  activities 
of  these  micro-organisms  at  various  temperatures.  The  direct  effects  of 
much  wider  ranges  of  temperatures  than  these,  if  not  continued  too  long, 
are  in  fact  extremely  slight,  proportionally,  in  the  case  of  must  and, 
when  evaporation  is  prevented,  of  wine.  Clear  grape-must  may  be 
subjected  to  any  temperature  between  0°  C.  and  80°  C.  (176°  F.)  for  a 
short  time  without  any  very  appreciable  effect  on  its  appearance,  flavor, 
or  chemical  composition.  The  same  is  true  of  wine,  if  at  the  higher 
temperatures  the  heating  is  done  in  such  a  way  as  not  to  cause  evap- 
oration of  the  alcohol. 

Practically  all  the  ill  effects  of  a  hot  fermentation,  i.  e.,  production  of 
volatile  acids  and  mannite,  failure  to  convert  all  the  sugar  into  alcohol, 
disagreeable  flavors,  persistent  cloudiness,  etc.,  are  due,  not  to  the  heat 
itself,  but  to  the  bacteria,  which  multiply  and  flourish  at  high  tempera- 
tures, and  to  the  weakened  yeast,  which  at  these  temperatures  becomes 
abnormal  and  acts  upon  the  must  in  a  way  very  different  from  its  normal 
and  healthy  action.  If,  then,  we  heat  a  must  to  40°  C.  (104°  F.)  arti- 
ficially when  there  are  no  bacteria  or  yeasts  present,  none  of  these 
undesirable  results  follow.  The  taste  common  in  wine  fermented  at 
high  temperature,  often  described  as  a  cooked  taste,  is  not,  therefore, 
due  to  the  heat  directly,  but  to  the  action  of  bacteria,  or  perhaps  to  the 
action  of  abnormal  yeast.*  A  real  cooked  taste,  that  is,  the  taste 
of  caramelized  sugar,  may  be  given  to  must  by  heating  it  too  high, 
and  this  is  in  fact  done  in  some  processes  of  wine-making  where  the 
must,  or  part  of  it,  is  concentrated  by  heating  in  boilers.  It  has  been 
shown  experimentally,  however,  that  must  may  be  heated  to  80°  C.f 
(176°  F.)  or  even  90°  C.  (194°  F.)  without  contracting  this  cooked  taste 
in  the  slightest  degree.  Where  this  taste  is  acquired  at  an  apparently 
lower  temperature,  it  is  due  to  the  fact  that,  owing  to  the  method  of 
heating  over  a  fire  or  by  means  of  superheated  steam  pipes,  some  of  the 
must  is  heated  much  higher  than  90°  C.  and  imparts  a  taste  to  the  whole. 

Another  taste,  undesirable  in  dry  wines,  often  associated  J  with  high 
temperatures,  is  that  of  "  rancio."  This  is  the  taste  acquired  by  wines 
upon  exposure  for  a  long  time  to  the  air.     The  taste  is  desirable  in 

*  This  is  well  shown  in  the  experiments  described  on  page  25. 

t  See  U.  C.  Bull.  130,  page  6. 

X  Barba,  in  "Annales  de  la  Soci^te"  des  Viticulteurs  de  France,"  vol.  VI,  p.  96. 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES.  21 

ports,  sherries,  and  other  sweet  and  liqueur  wines,  and  many  processes 
are  used  to  facilitate  and  hasten  its  acquirement.  All  these  processes 
aim  at  increasing  the  oxidation  of  the  wine,  either  by  fuller  exposure 
to  the  air  or  by  exposure  at  higher  temperatures.  This  taste  was  at 
one  time  accredited  to  the  action  of  a  fermentative  organism,  but  it  is 
now  well  known  to  be  due  to  simple  direct  oxidation.  Must  or  wine  ster- 
ilized and  kept  in  sterilized  vessels  in  contact  with  the  air  acquires  the 
taste  quite  as  quickly  as  when  unsterilized.  The  factors  which  deter- 
mine the  amount  of  the  taste  and  the  rapidity  with  which  it  is  acquired, 
are  the  temperature  and  the  exposure  to  the  air.  If  we  wish  to  prevent 
the  acquisition  of  "rancio,"  therefore,  we  must  avoid  undue  aeration  and 
high  temperatures.  That  exposure  to  high  temperatures  alone  con- 
tinued for  a  short  time  will  not  cause  a  wine  to  become  " rancio"  is 
proved  by  the  pasteurization  of  dry  wines  at  160°  F.  out  of  contact 
with  the  air.  It  has  also  been  proved  that  must  may  be  exposed  to  the 
same  temperature  under  the  same  conditions  with  equal  impunity. 
Moreover,  Professor  Barba,  of  the  CEnological  Station  at  Nimes,  has 
shown  that  must  and  grapes  can  be  heated  to  70°  C.  (176°  F.)  in  an 
open  vat  for  a  short  time  without  becoming  "  rancio."  At  the  Experi- 
ment Cellar  of  the  Agricultural  Department  of  the  University  of  Cali- 
fornia it  has  been  shown  that  grapes  can  be  heated  gradually  up  to  48°  C. 
(118^°  F.)  for  six  hours  without  any  special  precautions  to  exclude  the 
air,  and  acquire  no  taste  of  caramel  or  rancio.  In  fact,  wines  made 
from  grapes  heated  in  this  way  were  remarkable  for  their  clean  taste, 
freshness,  and  bouquet — qualities  associated  with  cool  fermentations. 

The  following  table  summarizes  the  main  effects  of  high  temperature 
in  the  making  of  dry  wine: 

A.  Direct  effects : — 

(a)  Beneficial : 

1.  Increase  of  color. 

2.  Increase  of  tannin. 

3.  Increase  of  body. 

(b)  Injurious: 

1.  Oxidation. 

2.  Caramelization. 

3.  Loss  of  alcohol. 

4.  Loss  of  bouquet  and  freshness. 

B.  Indirect  effects : — 
(a)  Beneficial: 

1.  Destruction    of   injurious    ferments  (sterilization)    in    the 
unfermented  must  (artificial  heating). 
(6)  Injurious: 

1.  Growth   of  injurious  ferments    in    the    fermenting    must 

(hot  fermentation). 

2.  Abnormal  excretions  of  the  yeast. 

In  order  to  utilize  our  raw  material  to  the  utmost  it  is  necessary  to 
devise  a  system  of  wine-making  which  will  combine  the  beneficial  effects 
of  heat  in  the  extraction  of  color,  tannin,  and  body  with  those  of  cool 


22 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


fermentation  in  producing  bouquet,  freshness,  and  maximum  amount 
of  alcohol.  This  is  what  is  done  to  a  certain  imperfect  extent  by  the 
Debono  method.  If  the  spontaneous  heating  of  the  pomace  which  occurs 
in  that  method  could  be  replaced  by  an  artificial  heating,  the  method 
would  be  more  nearly  perfect  and  more  under  control.  The  experiments 
of  Rosenstiehl,  Kiihn,  Mathieu,  and  others  in  sterilization  of  musts  for  the 
purpose  of  using  pure  and  selected  yeasts  have  shown  that  this  can  be 
done.  Their  methods,  however,  are  rendered  unnecessarily  trouble- 
some and  expensive  by  attempting  to  effect:  (1)  complete  sterilization, 
and  (2)  complete  absence  of  air.  The  researches  of  Kayser  and  Barba 
show  that  neither  of  these  objects  are  necessary  for  the  ordinary  pur- 
poses of  wine-making,  and  their  results  have  been  fully  corroborated  by 
tests  made  at  the  California  Experiment  Station  at  Berkeley. 

Extraction  of  Color  and  Tannin  by  Heat. — In  1898  a  series  of  experi- 
ments was  made  at  Berkeley  to  determine  to  what  extent  color  and 
tannin  could  be  extracted  before  fermentation  by  direct  heating  of  the 
grapes.     A  summary  of  the  results  is  shown  in  the  following  table: 

TABLE  I.     Extraction  of  Color  and  Tannin  from  Fresh  Grapes  by  Heat. 


<i 


—— 


/  17 


1.  Witness.     (Ordinary  fermentation  at  30°  C.) 


2.  Heated  to  50°  C.  in  one  hour 1.00  hour 

(a)  Kept  at  50°  C.  for  30  minutes  longer  _ .  1.50 
(6)  Kept  at  50°  C.  for  90  minutes  longer  ._  2.50 

3.  Heated  to  60°  C.  in  80  minutes '..  1.30 

(a)  Kept  at  60°  for  60  minutes  longer 2.30 

(6)  Kept  at  60°  C.  for  120  minutes  longer  .  3.30 

4.  Heated  to  70°  C.  in  90  minutes 1.50 

(a)  Kept  at  70°  C.  for  45  minutes  longer  ..  2.25 
(6)  Kept  at  70°  C.  for  90  minutes  longer ..  3.00 

5.  Heated  to  65°  C.  in  3  hours  and  20  minutes,  after 

adding  10.5%  alcohol t 


Color. 


Tint. 


2  VR 

5VR 

3  VR 
2  VR 

VR 

*VR+ 
VR+ 

VR+ 

VR-j- 
VR+ 


VR 


In- 
tensity. 


66.6 

19.3 
37.7 
74.0 

95.0 
133.0 
174.0 

138.0 
160.0 
160.0 


120.0 


Tannin 


.357 

.108 
.135 
.217 

.328 
.385 
.500 

.246 
.369 
.450 


.552 


Acid. 


.45 

.38 
.37 
.30 

.50 
.45 
.52 

.48 
.46 
.46 


.38 


*The  +  indicates  the  color  brighter  than  the  first  tint  of  the  colorimeter, 
t  Corrected  for  dilution  and  contraction  due  to  the  addition  of  alcohol. 

With  regard  to  the  extraction  of  color,  an  inspection  of  the  intensity 
shows  that  heating  the  grapes  for  two  hours  and  a  half  at  50°  C.  (122°  F.) 
extracted  more  color  than  an  ordinary  fermentation  at  30°  C.  (86°  F!), 
while  heating  them  for  about  the  same  time  at  60°  C.  (140°  F.)  or  one 
hour  and  a  half  at  70°  C.  (158°  F.)  extracted  about  twice  as  much.  Still 
longer  heating  extracted  still  more  color,  the  maximum  being  about 
three  times  that  of  the  ordinary  fermentation.  It  may  be  noted  at 
t  be  same  time  that  the  kind  of  color  or  tint  was  in  all  cases  better  than 
that  of  the  fermented  wine,  except  where  the  heating  had  been  insuf- 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES. 


23 


ficient.  Heating  for  one  hour  and  a  half  at  50°  C.  was  insufficient  to 
properly  extract  the  color,  either  as  regards  tint  or  intensity.  In  all 
the  other  cases  the  color  was  not  only  better  than  that  of  the  fermented 
wine,  but  extended  beyond  the  limits  of  the  scale  toward  the  VR  end, 
showing  that  it  was  better  than  that  of  any  wines  ordinarily  found  in 
France  where  the  scale  is  adopted. 

It  has  been  objected  that  the  color  extracted  by  heat  in  this  manner 
is  of  a  different  nature  from  that  extracted  by  fermentation,  and  that 
most  of  it  would  be  deposited  by  the  alcohol  formed  during  fermenta- 
tion. The  fifth  experiment,  at  the  bottom  of  the  column,  shows  that, 
while  this  may  be  partly  true,  yet  with  the  addition  of  10-£%  of  alcohol 
before  the  heating,  twice  as  much  color  was  extracted  in  3^  hours  at 
65°  C.  (149°  F.)  as  by  fermentation,  and  that  the  tint  was  better. 

.  In  order  to  test  whether  this  destruction  or  precipitation  of  color  by 
the  alcohol  continued  on  further  contact,  the  tests  summarized  in  the 
following  table  were  made. 

A  quantity  of  Lagrein  grapes  from  Tulare  was  crushed  and  heated  to 
70°  C.  to  extract  the  color.  The  must  contained  27.4%  of  solid  contents 
by  spindle  and  .47%  of  acid  calculated  as  tartaric.  The  color  of  the 
must  at  the  commencement  of  the  experiment  (September  23,  1899) 
was  VR  85.3.  The  colored  must  was  placed  in  ten  bottles  holding 
125  c.c.  each,  and  various  amounts  of  alcohol  added  to  each.  Two 
series  were  made,  to  one  of  which  was  added  .4%  of  tartaric  acid.  The 
bottles  were  filled  quite  full,  well  corked,  and  sterilized  at  60°  C,  in 
order  to  eliminate  as  much  as  possible  the  influence  of  oxygen  and 
fermentative  organisms. 

TABLE  II.     Effect  of  various  amounts  of  Alcohol  and  Tartaric  Acid  on  the  Stability  of  the 
Coloring  Matter  of  Red  Grapes.     Color  after  6|  Months. 


No  Acid  Added. 


Tint. 


In- 
tensity.* 


Acid  Added. 


Tint. 


In- 
tensity.* 


1.  Must  +  0%  of  alcohol 

2.  Must-}-  5%  of  alcohol 

3.  Must  + 10%  of  alcohol 

4.  Must -f- 15%  of  alcohol 

5.  Must  4-20%  of  alcohol 


2  VR 

2  VR 

3  VR 

3  VR 

4  VR 


57.9 
53.2 
39.6 
41.1 
41.2 


VR 
VR 
VR 
VR 
VR 


58.8 
56.9 
57.7 
55.8 
56.6 


*  These  figures  are  corrected  for  the  dilution  and  contraction  due  to  the  addition  of  alcohol. 


No.  1  shows  that  the  must  to  which  no  alcohol  was  added  lost  32%  of 
its  color  in  six  months,  and  that  this  loss  was  not  prevented  by  the 
addition  of  a  considerable  quantity  of  tartaric  acid.  The  must  to  which 
was  added  5%  of  alcohol  lost  38%  of  its  color,  and  that  with  10%  of 
alcohol  46%.  The  addition  of  15%  and  20%  of  alcohol  had  no  more 
effect  in  destroying  coloring  matter  than  10%,  though  there  was  a  slight 
degradation  of  tint.     The  last  column  shows  that  the  addition  of  tar- 


24  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

taric  acid  was  very  effective  in  counteracting  the  effect  of  the  alcohol 
as  the  loss  of  color  due  to  alcohol  where  tartaric  acid  was  added  aver- 
aged only  34%,  or  very  little  more  than  that  of  the  pure  must. 

That  heating  the  grapes  is  equally  effective  in  extracting  the  tannin 
is  well  shown  by  Table  I.     The  tests  indicate  that,  with  the  grapes  used, 
sufficient  tannin  is  extracted  before  the  maximum  color  extraction  is 
reached.     They   also  indicate    that  there  is  danger  that  too  long  or 
too   high  heating  may  extract  too  much  tannin,  and  that  it  may  be 
impossible  to  get  the  maximum  color  extraction  without  getting  too 
much  tannin.     However,  test  4a  shows  that  twice  the  color  may  be 
obtained  by  heating  to  70°  C.  (158°  F.)  for  an  hour  and  a  half  before 
the  tannin-content  reaches  that  of  an  ordinary  fermentation.     With 
further  heating  more  tannin  may  be  obtained,  and  the  maximum  was 
not  reached  in  any  of  the  tests.     Undoubtedly,  prolonged  heating  would 
dissolve  some  of  the  tannin  in  the  seeds,  so  that  the  astringency  could 
probably  be  increased  as  much  as  desired,  even  with  grapes  normally 
lacking  in  tannin.     The  presence  of  too  much  tannin  is  much  less  dan- 
gerous than  too  little,  as  it  increases  the  keeping  qualities  of  the  wine 
and  disappears  gradually  with  age  or  can  be  removed  to  a  great  extent 
by  fining.     Moreover,  Professor  Barba  has  shown  that  the  tannin  in  the 
must  is  very  rapidly  eliminated  if  the  must  is  kept  without  fermentation.* 
If,  therefore,  it  is  necessary  to  heat  the  grapes  for  a  long  time  to  extract 
the  color,  the  superfluous  tannin  can  be  diminished  to  any  desired  extent 
by  delaying  the  fermentation. 

These  laboratory  experiments  demonstrated  the  probability  that 
color  and  tannin  could  be  extracted  by  heat,  the  red  must  separated 
from  the  pomace  and  fermented  in  the  same  manner  as  white  wine.  If 
this  could  be  done  without  deterioration  of  quality  from  some  unfore- 
seen cause,  a  great  advance  would  have  been  made  in  the  certainty  of 
making  good  wine  in  hot  localities.  The  cool  fermentation  of  must 
without  the  pomace  is  a  comparatively  simple  operation. 

While  these  laboratory  tests  were  in  progress,  corresponding  wine- 
making  tests  were  undertaken  in  the  cellar  to  throw  light  on  the  feasi- 
bility of  the  method  in  actual  practice. 

About  three  quarters  of  a  ton  of  red  grapes  was  obtained  from  the 
Tulare  Experiment  Station.  These  grapes  were  grown  in  black,  alkaline, 
sandy  soil  in  one  of  the  hottest  regions  of  the  State,  where  all  the  con- 
ditions which  are  supposed  to  render  a  hot  region  unsuitable  for  the 
production  of  dry  wine  are  at  their  worst.  The  grapes  consisted  of 
Lagrein  75%,  Malbec  14%,  and  Valdepenas  11%,  and  the  mixture  con- 
tained 24.64%  of  fermentable  sugar  and  .34%  of  acid  calculated  as  tar- 

*  Barba,  M.,  in  "Annales  de  la  SociSte*  des  Viticulteurs  de  France,"  vol.  VI,  p.  100: 

Tannin  in  must  of  heated  grapes  immediately  after  heating _. .910 

Tannin  in  wine  of  heated  grapes  fermented  immediately  after  heating  _ 820 

Tannin  in  must  of  heated  grapes  one  day  after  heating .720 

Tannin  in  must  of  heated  grapes  four  days  after  heating . .260 


MANUFACTURE   OF    DRY   WINES   IN   HOT    COUNTRIES. 


25 


taric.  The  grapes  were  therefore  totally  unfitted  for  the  production  of 
dry  red  wine  by  the  ordinary  methods  of  wine-making.  Grapes  with 
such  high  sugar-content  and  low  acidity  would  fail  to  ferment  dry, 
not  only  in  the  San  Joaquin  Valley  but  in  any  part  of  California,  and, 
in  nine  cases  out  of  ten,  the  tanks  would  almost  certainly  "stick"  in 
fermentation,  and  the  wine  spoil  before  it  was  three  months  old.  No 
grapes  more  suitable  to  detect  any  weak  point  in  the  method  could  have 
been  chosen. 

One-fifth  of  the  crushed  and  mixed  grapes  was  fermented  in  the 
ordinary  way  in  an  open  fermenting  vat.  More  than  the  usual  care 
was  taken,  the  grapes  being  thoroughly  stirred  twice  a  day  and  the  vat 
kept  covered.  The  fermentation  was  cool,  never  exceeding  79°  F.,  and 
the  wine  was  nearly  dry  at  the  end  of  thirteen  days. 


Fig.  1. 


Heating  Vat.  Cooling  Vat. 

Heating  and  Cooling  Vats.    Showing  the  plan  adopted  for  heating  the  grapes  and 
cooling  the  must  before  fermentation. 


The  other  four-fifths  of  the  crushed  grapes  was  placed  in  a  small 
fermenting-vat,  which  they  about  two-thirds  filled.  At  the  bottom  of 
this  vat  was  a  coil  of  half-inch  block-tin  tubing,  through  which  a  stream 
of  water  of  a  temperature  of  80°  C.  (176°  F.)  was  run.  The  vat  was 
then  covered  with  a  canvas  sheet,  which  was  removed  every  half  hour 
and  the  heating  grapes  thoroughly  stirred.  The  heating  commenced  at 
10  a.  m.,  the  temperature  of  the  grapes  being  18.5°  C.  (65°  F.),  and 
continued  until  4  p.  m.,  when  the  temperature  of  the  grapes  had  risen 
gradually  to  48°  C.  (118°  F.).  The  red  must  was  then  drawn  off  and 
mixed  with  the  must  pressed  from  the  heated  pomace,  and  placed  in  an 
open  vat  (see  Fig.  1). 

The  color  of  the  must,  as  it  ran  from  the  heater,  was  1  VR  —  78,  and 
of  that  which  ran  from  the  press  VR  — 102.     The  amount  of  tannin 


26 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


in  the  mixture  was  .262%.  The  must  was  cooled,  immediately  after 
mixing,  to  30°  C.  (86°  F.)  by  means  of  a  coil  similar  to  the  heating 
coil,  through  which  water  at  20°  C.  (68°  F.)  was  run.  It  was  then 
divided  into  four  equal  lots,  numbered  2717a,  27176,  2717c,  and  2717d, 
each  of  which  was  placed  in  a  separate  keg.  Nos.  27176  and  2717rf  each 
received  an  addition  of  tartaric  acid.  Fermentation  was  started  by  the 
addition  of  yeast  and  was  finished  in  all  cases  in  twelve  days,  the  tem- 
perature being  practically  the  same  as  that  of  the  ordinary  fermenta- 
tion, never  exceeding  26°  C.  (79°  F.).  As  soon  as  the  wines  were  dry 
they  were  racked  into  clean  casks,  kept  for  a  few  days  in  the  fermenting- 
room  at  21°  C.  (70°  F.),  and  as  soon  as  clear  racked  again  and  put  in 
the  cool  storage  cellar.  The  wine  fermented  in  the  ordinary  way 
received  the  same  treatment  after  fermentation.  Some  of  the  data 
obtained  are  shown  in  the  following  table: 


Must. 

Wine. 

Acid. 

Acid. 

Tannin. 

Alcohol.   Co^ts< 

Time  of 
Fermen- 
tation. 

Color. 

Witness:   2717 

.34 
.54 
.60 
.44 
.53 

.38 
.41 
.60 
.47 
.53 

13  days 
12  days 
12  days 
12  days 
12  days 

3  VR    30.7 

f  2717a 

Heated  J   27176 

grapes.  1   2717c 

I  2717d- 

.151 
.153 
.153 
.139 

14.25 
14.10 
13.90 
14.10 

3.15 
2.81 
3.15 
2.60 

2  VR    29.2 
2VR    35.7 
2  VR    25.0 
2  VR    32.0 

The  four  wines  made  from  the  heated  grapes  were  bottled  when  they 
were  eighteen  months  old,  and  were  in  excellent  condition.  They 
remained  in  the  cellar  four  years,  when  they  were  opened  and  tasted. 
They  were  all  perfectly  sound  and  clear.  A  thin,  tightly  adhering 
deposit  had  been  formed  in  the  bottles,  proving  by  its  character  the 
perfect  keeping-qualities  of  the  wine.  The  wines  were  fresh,  clean  tast- 
ing, and  of  good  color.  The  bouquet  was  remarkably  strong,  proving 
conclusively  that  heating  the  grapes  to  48°  C.  does  not  diminish  this 
quality  in  the  wine,  and  even  tending  to  show  that,  on  the  contrary,  it 
increases  it. 

This  series  of  tests  has  clearly  demonstrated  a  fact  of  great  impor- 
tance to  wine-makers  of  the  interior  valleys,  viz:  that  grapes  grown  in 
rich,  sub-irrigated  soil  in  the  hottest  part  of  the  valley  can,  if  properly 
handled,  be  used  for  the  production  of  not  only  a  sound  dry  red  wine, 
but  of  a  wine  of  exceptional  quality,  superior  in  every  respect  to  the 
bulk  of  the  wines  produced  in  any  part  of  California  or  of  Europe. 
Whether  fine  wines,  equal  to  the  best  of  the  Medoc  and  Burgundy  or  of 
the  coast  valleys  of  California,  can  be  produced  there  is  a  matter  of 
much  less  importance  at  present,  and  can  be  left  for  the  future  to 
decide. 


MANUFACTURE    OF    DRY   WINES    IN    HOT    COUNTRIES.  27 

ADDITION    OF    SUBSTANCES    DEFICIENT    IN    THE    GRAPES. 

Water. — One  of  the  most  frequent  causes  of  difficult  fermentation  and 
spoiled  wine,  when  the  attempt  is  made  to  make  dry  wine  in  a  hot  cli- 
mate, is  extreme  sweetness  of  the  grapes.  Under  the  most  favorable 
conditions  it  is  impossible  to  cause  the  transformation  into  alcohol  of 
more  than  about  28%  of  sugar  in  the  must,  and  this  only  after  a  very  long 
time.  Under  ordinarily  favorable  conditions  it  is  impracticable  to  fer- 
ment out  more  than  25%,  producing  14.5%  of  alcohol.  Under  the  condi- 
tions existing  in  an  ordinary  cellar  in  a  warm  locality  the  limit  is  much 
lower,  and  may  be  taken  as  somewhere  about  22%  of  actual  fermentable 
sugar,  corresponding  to  between  22.5%  and  23%  on  Balling's  saccharom- 
eter,  and  capable  of  yielding  a  wine  containing  13%  of  alcohol.  Even 
with  this  amount  of  sugar,  most  of  the  fermenting  vats  will  "  stick  " 
with  2%  to  4%  of  unfermented  sugar  in  warm  seasons  with  ordinary 
methods  of  wine-making.  Grapes  containing  only  19%  of  fermentable 
sugar  can,  however,  be  nearly  always  fermented  dry  with  the  ordinary 
methods,  except  in  very  hot  seasons  or  where  very  large  fermenting- 
vats  are  employed. 

As  about  three  quarters  of  the  weight  of  ripe  grapes  consists  of  water, 
the  addition  of  a  little  more  when  there  is  too  much  sugar  naturally 
suggests  itself.  The  procedure  has  been  and  is  still  frequently  used, 
but  often  with  but  indifferent  success.  The  reasons  for  failure  are  two: 
Firstly,  the  dilution  of  the  sugar  entails  at  the  same  time  the  dilution 
of  the  other  constituents  of  the  must,  notably  the  acid;  and  secondly, 
impure  water  is  often  used,  water  containing  large  amounts  of  salts  or 
of  organic  matter,  wdiich  materially  alters  the  flavor  of  the  wine  and 
the  character  of  the  fermentation.  The  dilution  of  the  acid  is  the  most 
serious  defect,  and  is  the  more  serious  the  riper  the  grapes,  for  the  more 
sugar  there  is  present  usually  the  less  there  is  of  acid.  For  example: 
if  we  dilute  a  must  containing  24  grams  of  sugar  in  100  c.c.  (about  24.4%? 
Balling)  and  .4%  of  acid  to  22^  (23.2%,  Balling),  by  adding  7%  of 
water  we  also  reduce  the  acid,  which  is  already  too  low,  to  .37%. 
Wherever  dilution  is  practiced,  therefore,  it  is  almost  always  necessary 
to  supplement  the  acidity.  Moreover,  the  practice  can  be  used  success- 
fully only  where  the  grapes  are  naturally  high  in  extract  and  coloring 
matter.  In  other  cases  the  wine  will  be  thin  and  flat.  There  is  a  well- 
founded  prejudice  against  adding  water  to  wine  either  before  fermentation 
or  after.  This  has  its  origin,  to  a  great  extent,  in  the  fact  that  in 
Europe  the  addition  of  water  is  done  for  purposes  of  fraud,  with  the 
simple  object  of  making  more  gallons  of  wine  out  of  a  given  quantity  of 
grapes.  The  addition  of  water  to  the  wine  after  the  fermentation  is 
never  admissible  under  any  circumstances,  as  it  can  never  improve  the 
quality  in  any  way,  and  will,  in  fact,  always  injure  it.  There  are,  how- 
ever, cases  where  it  is  possible,  by  a  limited  amount  of  dilution  before 


28  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION. 

fermentation,  to  produce  a  good,  sound,  dry  wine,  where  it  would  be  very 
difficult  to  do  so  without.  This  applies  particularly  to  California,  where 
the  richness  of  the  grapes  in  all  constituents  except  acid  is  often  so 
great  that  even  after  the  addition  of  a  certain  amount  of  water  to  the 
must  the  resulting  wine  has  a  higher  degree  of  alcohol  and  extract  than 
the  bulk  of  European  wines,  and  could  not  be  recognized  as  watered  by 
any  "alcohol  and  acid"  or  other  chemical  or  organoleptic  test.  How- 
ever, the  practice  is  to  be  commended  only  under  exceptional  circum- 
stances, as  there  are  almost  always  better  ways  of  attaining  the  object — 
a  thorough,  clean  fermentation. 

Tartaric  Acid. — This  acid  is  found  in  larger  or  smaller  amounts  in  all 
grapes  and  in  all  wines.  Some  of  the  acid  exists  "  free  "  (that  is,  uncom- 
bined  with  any  base),  but  most  of  it  occurs  in  combination  with  potash  and 
lime.  The  principal  acidity  of  most  grapes  and  wines  is  due  to  the 
acid  salt  of  potash  and  tartaric  acid,  bitartrate  of  potash,  more  com- 
monly known  as  cream  of  tartar.  Malic  acid  and  its  salts  also  occur 
in  considerable  amounts,  and  some  other  acids  in  very  small  amounts. 
Thus  the  acidity  of  a  must  is  due  to  a  number  of  acids  and  acid  salts, 
which  vary  somewhat  in  their  proportions  as  well  as  in  their  total 
amounts  in  various  grapes  and  at  various  stages  of  ripeness.  In  unripe 
grapes  the  free  acids  predominate;  in  ripe,  the  acid  salts. 

The  importance  of  the  acidity  of  the  grapes  in  wine-making  is  so 
great  that  no  wine-maker  should  be  without  the  means  of  determining 
its  amount.  It  is  not  necessary  to  know  the  exact  amount  of  each  con- 
stituent of  the  acidity,  and  to  determine  it  would  be  difficult  and  imprac- 
ticable in  wine-making;  but  some  measure  of  the  "total  acidity,"  which 
will  give  us  an  idea  of  its  effect  on  the  fermentation  and  on  the  quality 
of  the  wine,  is  both  useful  and  necessary.  This  may  be  found  in  vari- 
ous ways,  but  the  results  are  always  given  as  sulfuric  or  tartaric  acid. 
That  is,  when  we  say  a  must  has  .8%  acid  as  tartaric,  we  mean  that  its 
acidity  has  the  same  effect  on  the  reagents  used  in  determining  it  as 
.8%  of  pure  tartaric  acid  would  have.  This  does  not  give  us  the  exact 
amount  of  tartaric  or  of  any  of  the  acids  in  the  must,  but  as  the  vari- 
ous acid  constituents  occur  in  about  the  same  relative  proportions  in 
all  grapes  that  are  not  very  unripe,  it  gives  us  a  convenient  way  of 
comparing  different  grapes  and  of  judging  whether  their  acidity  is  suf- 
ficient for  our  purpose. 

The  acidity  affects  the  quality  of  the  wine  both  directly  and  by  its 
effect  on  the  fermentation.  A  dry  wine  requires  a  certain  amount  of 
acidity  or  it  will  taste  flat — a  red  wine  with  insufficient  acidity  drops 
its  color  very  rapidly.  Its  most  marked  effect,  however,  is  due  to  its 
influence  on  the  fermentative  organisms  in  the  must.  Yeast  will  mul- 
tiply and  grow  in  presence  of  a  larger  amount  of  acid  than  any  of  the 
ordinary  disease  germs  and  bacteria  occurring  in  must  and  wine.      For 


MANUFACTURE   OF    DRY   WINES   IN   HOT    COUNTRIES.  29 

this  reason  a  very  acid  must  nearly  always  undergoes  a  clean  and 
thorough  fermentation,  and  the  resulting  wine  clears  rapidly  and  keeps 
well. 

It  is  impossible  to  say  what  the  most  desirable  degree  of  acidity  is, 
as  this  varies  with  so  many  conditions.  Red  wine  requires  more  than 
white,  as  the  former  loses  much  in  fermenting.  Coloring  grapes,  such 
as  the  Bouschets,  require  more  than  ordinary  red  grapes,  as  the 
coloring  matter  is  less  stable.  American  grapes,  such  as  Lenoir,  require 
still  more,  as  they  are  liable  to  a  peculiar  change  when  lacking  in  acid, 
which  destroys  their  color.  Moldy,  unripe  or  otherwise  defective  grapes 
require  more  than  good  grapes,  on  account  of  the  large  numbers  of 
bacteria  and  molds  they  contain. 

According  to  Bouffard,*  the  average  acidity  of  good  red  wines  in  the 
south  of  France  is  .6%  to  .9%.  Good  wines  may  have  less  than  this, 
but  they  are  then  difficult  to  handle.  As  some  of  the  acidity  is  lost  in 
fermentation,  the  must  should  have  more  than  this.  Roos  f  gives  as 
the  most  favorable  acidity  for  red  wine  grapes  in  the  south  of  France, 
the  following: 

For  Aramon,  Carignane,  and  most  red  grapes 0.8% 

For  Bouschets 1.0% 

For  Jacquez(  Lenoir) 1.2% 

The  acidity  of  ripe  California  grapes  very  rarely  reaches  these  figures, 
especially  in  the  hotter  parts,  and  this  lack  greatly  intensifies  the  un- 
favorable effect  of  hot  fermentation.  Even  in  the  south  of  France  the 
grapes  very  commonly  fall  below  these  figures  when  allowed  to  mature 
completely.  There,  the  difficulty  is  usually  overcome  by  gathering  the 
grapes  under-ripe,  to  the  detriment,  as  already  observed,  of  both  quality 
and  quantity.  In  large  vineyards,  however,  it  is  often  impossible  to 
gather  all  the  grapes  before  they  are  thoroughly  ripe,  so  the  augmenta- 
tion of  the  acidity  by  addition  of  acid  to  the  grapes  or  wine  is  becoming 
a  common  practice  both  there  and  in  Algeria.  The  addition  of  the  acid 
to  the  wine  after  fermentation  is  practiced  only  when  its  object  is  to 
increase  the  acidity  for  the  taste  of  certain  French  markets,  or  to  increase 
the  stability  of  the  coloring  matter  in  wine  from  color-grapes.  Jacquez 
wine  is  sometimes  dosed  with  tartaric  acid  to  the  extent  of  2%,  which 
makes  it  quite  undrinkable  but  useful  to  blend  with  wines  lacking  in 
both  acid  and  color.  Tartaric  acid  added  to  the  wine  after  fermenta- 
tion gives  a  harshness  to  the  wine  which  is  absent  when  the  acid  is 
added  to  the  must  before  fermentation.  The  only  object  of  adding  it 
after  instead  of  before  is  that  a  certain  proportion  is  precipitated,  and 
this  in  the  latter  case  is  lost  in  the  pomace  or  thick  lees,  while  in  the 
former  it  is  recovered  in  the  argol  deposited  in  the  casks. 

*  "  Revue  de  Viticulture,"  vol.  10,  p.  545. 

t  Roos:  "L' Industrie  Vinicole  Meridionale."     Montpellier,  1898. 


30  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 

For  the  purpose  of  regulating  the  fermentation,  however,  it  must  be 
added  to  the  crushed  grapes,  and  in  this  case,  unless  used  in  extrava- 
gant quantities,  it  has  absolutely  no  ill  effects  on  the  flavor  of  the  wine. 
How  much  it  is  necessary  or  safe  to  use  can  be  determined  only  by 
experiment  in  each  vineyard  with  each  variety  of  grape.  In  a  general 
way,  it  may  be  said  that  experience  has  shown  that  with  grapes  very 
low  in  acidity  it  is  neither  safe  nor  necessary  to  add  enough  acid  to 
bring  up  the  amount  to  the  figures  given  by  Roos  as  normal.  For 
example,  if  a  must  shows  .4%  of  acidity  it  is  usually  sufficient  to  add 
enough  tartaric  acid  to  bring  this  acidity  up  to  .6%,  that  is  4  pounds  to 
the  ton  of  grapes.  Some  writers  say  it  is  rarely  desirable  to  exceed  2 
pounds  to  the  ton,*  while  others  believe  it  is  quite  admissible  to  go  as 
high  as  5,  6,  or  even  8  pounds  per  ton.f  In  general,  the  best  modern 
practice  seems  to  be  not  to  exceed  4  pounds  per  ton, J  and  this  in  all 
cases  is  sufficient  to  insure  a  good  fermentation  so  far  as  acidity  alone 
can  do  this.  The  reason  of  this  is  that  the  addition  of  a  certain  amount 
of  tartaric  acid  to  the  must  has  a  much  stronger  effect  on  regulating  the 
fermentation  than  an  equivalent  amount  of  natural  acidity,  because  it 
increases  the  "free"  acid  and  diminishes  the  ''combined  acid"  or  cream 
of  tartar.  The  former  has  a  much  more  deterrent  effect  on  bad  ferments 
than  the  latter,  but  when  in  great  excess  it  also  has  an  unpleasant 
harshness  to  the  palate.  When  we  add  tartaric  acid  to  a  must  or  wine 
we  get  an  increase  of  free  tartaric  acid  in  the  liquid,  but  at  the  same 
time  we  get  a  diminution  of  cream  of  tartar.  The  chemical  reactions 
to  which  this  is  due  are  obscure  and  complicated,  but  it  is  partly  due  to 
the  fact  that  the  more  free  tartaric  acid  there  is  present  the  less  capable 
the  wine  is  of  keeping  bitartrate  of  potash  in  solution.  The  addition  of 
tartaric  acid  always  causes,  therefore,  a  deposit  of  cream  of  tartar,  and 
therefore  the  increase  in  the  acidity  of  the  resulting  wine  is  less  than 
corresponds  to  the  amount  of  acid  added.  In  a  general  way  we  may 
say  that  we  usually  find  in  the  wine  about  two-thirds  of  the  acid  added 
to  the  must.  The  amount  will  vary,  however,  according  to  conditions. 
If  added  directly  to  the  wine  we  may  increase  the  acidity  by  70%  of  the 
acid  used.*  If  added  to  the  must  only  47%  may  be  found  in  the  wine,§ 
while  if  added  to  the  crushed  grapes  as  little  as  25%  §  may  remain. 

There  is  very  little  danger  of  making  the  wine  harsh  unless  the  maxi- 
mum doses  recommended  are  very  much  exceeded;  and  a  slight  harsh- 
ness due  to  good  acidity  diminishes  with  age. 

Citric  Acid. — This  acid  has  been  used  extensively  during  recent 
years  to  cure  or  prevent  a  certain  form  of  the  disease  of  wines  which 
the  French  call  "la  casse."     Its  efficacy  in  this  respect,  and  the  com- 

*  Bouffard,  A. :  "  Revue  de  Viticulture,"  vol.  10,  p.  546. 

tSebastian,  V:  "Le  Sucrage  des  Vins,"  p.  46.    Montpellier,  1903. 

JPacottet:  "Vinification,"  p.  33.    Paris,  1904. 

§FonHecaand  Chiaramonte,  quoted  by  Pacottet,  P.:  "Vinification,"  i>.  74. 


MANUFACTURE    OF    DRY    WINES    IN    HOT    COUNTRIES.  31 

plete  absence  of  any  injurious  effect  on  the  wines  treated,  suggested  its 
use  in  the  acidification  of  deficient  must,  before  fermentation,  in  place 
of  tartaric  acid.  For  this  purpose  it  has  been  found  equally  efficacious 
and,  from  most  points  of  view,  superior  to  tartaric  acid.  The  only  objec- 
tion to  its  use  is  the  doubt  as  to  the  presence  of  citric  acid  as  a  normal 
constituent  of  grapes.  Some  investigators  claim  that  it  does  exist  natu- 
rally in  grapes  in  minute  quantities,  and  as  only  minute  quantities  are 
needed,  and  as  the  acid  is  as  "innocuous  and  wholesome  as  tartaric 
acid,"  there  seems  to  be  no  reasonable  objection  to  its  use.  It  is 
not  and  can  not  be  used  in  any  way  to  increase  the  quantity  of  wine 
made  from  a  given  quantity  of  grapes,  but  only  to  improve  its  quality. 
Its  use  can  not  therefore  be  considered  a  sophistication  any  more  than 
that  of  sulfurous  acid  or  finings. 

Citric  acid  has  several  advantages  over  tartaric.  It  does  not  give 
the  harshness  to  the  wine  which  some  tasters  find  in  case  of  large  addi- 
tions of  tartaric.  It  does  not  cause  precipitation  of  the  cream  of  tartar, 
but  on  the  contrary  makes  this  latter  slightly  more  soluble.  This,  together 
with  the  fact  that  it  seems  to  have  a  slightly  more  deterrent  effect  on 
bacteria  than  tartaric,  makes  it  possible  to  get  the  same  effect  with  a 
much  smaller  amount.  From  one  half  to  one  third  the  amount  is  used. 
That  is,  for  example,  where  it  would  be  necessary  to  add  6  pounds  of 
tartaric  acid  to  a  ton  of  grapes,  from  2  to  3  pounds  of  citric  acid  would 
be  equally  effective. 

It  is  essential  that  the  citric  acid  should  be  pure.  Citric  acid  is 
sometimes  found  on  the  market,  marked  for  dyer's  uses,  which  is  adul- 
terated with  oxalic  acid.  This  would  be  extremely  injurious  to  the 
wine.  There  is,  however,  no  difficulty  now  in  getting  pure  citric  acid 
in  quantities  at  about  30  cents  per  pound,  which  is  very  little  more 
than  the  cost  of  tartaric,  and  which,  considering  the  smaller  amounts 
needed,  makes  it  more  economical  than  the  latter.  Citric  acid  of  suit- 
able quality  is  now  made  in  quantity  in  California  from  refuse  and  cull 
lemons. 

Citric  acid  must  not  be  confused  with  lemon  oil  or  essence  obtained 
from  the  skins  of  lemons  and  used  for  flavoring.  Pure  citric  acid  has 
a  completely  clean,  simple,  acid  taste,  without  any  lemon  flavor  what- 
ever. 

Plaster. — One  of  the  oldest  and  most  widespread  methods  of  aiding 
the  fermentation  by  increasing  the  acidity  of  the  must  is  by  the  addi- 
tion of  ordinary  plaster  of  Paris  or  sulfate  of  lime  to  the  grapes.  The 
plaster  is  sifted  on  to  the  grapes,  as  they  come  from  the  crusher,  at  the 
rate  of  between  4  and  8  pounds  to  the  ton.  The  practice  was  formerly 
almost  universal  in  southern  France  and  similar  climates,  but  it  has 
been  greatly  restricted  by  a  law  passed  in  1891,  limiting  the  amount  of 
sulfate  of  potash  in  wines  to  2  grams  per  liter. 


32  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

The  effect  of  the  plaster  is  to  cause  a  better  fermentation  and  to  increase 
the  keeping  quality  of  the  wine.  It  aids  in  the  rapid  clearing  of  the 
wine  and  increases  and  brightens  the  color.  The  chemical  action  is 
somewhat  complex,  but  the  final  result  is  an  increase  in  the  acidity  of 
the  wine  and  of  the  sulfate  of  potash.  The  lime  sulfate  acts  on  the 
potash  salts  existing  naturally  in  the  wine,  forming  insoluble  lime 
tartrates,  which  are  deposited,  and  soluble  sulfates  and  acid  sulfates, 
which  remain  in  the  wine.  The  acid  sulfates  finally  take  the  pot- 
ash from  the  organic  salts  and  become  neutral  sulfates  of  potash, 
setting  free  the  organic  acids  to  increase  the  acidity  of  the  wine.  When 
plaster  of  good  quality  is  used  it  is  a  very  cheap,  effective,  and  easily- 
applied  means  of  assisting  the  fermentation,  and  is  greatly  in  favor 
among  the  wine-makers  of  nearly  all  warm  regions.  While  very  help- 
ful in  obtaining  a  sound,  clear  wine  of  good  keeping  qualities,  it  gives 
a  certain  harshness  which  is  inadmissible  for  fine  wines.  Many  sam- 
ples of  plaster,  moreover,  contain  carbonates,  which  make  its  use  very 
unreliable,  and  if  present  in  any  considerable  quantities  neutralize 
more  of  the  natural  acidity  of  the  wine  than  is  set  free  by  the  sulfate. 

The  question  of  the  harmful  effects,  on  health,  of  wine  containing 
sulfate  of  potash  is  still  in  dispute.  The  law  in  France,  however,  lim- 
iting the  amount  that  a  commercial  wine  may  contain  to  2  grams  per 
liter,  makes  impossible  the  use  of  enough  plaster  to  have  the  desired 
effect  on  the  fermentation.  For  this  reason  its  use  is  much  more 
restricted  than  formerly.  Some  wine-makers  use  it  in  conjunction  with 
tartaric  acid,  using  as  much  plaster  as  possible  without  exceeding  the 
legal  limit  of  sulfate  in  the  wine,  and  making  up  the  deficiency  with 
tartaric  acid. 

Phosphates. — Latterly  many  wine-makers  in  Algeria  have  been  using 
bi-basic  phosphate  of  lime  in  the  same  way  as  plaster.  It  is  sifted  on  to 
the  crushed  grapes  in  the  same  way  and  produces  very  much  the  same 
effect.  It  is  superior  to  plaster,  as  it  does  not  give  the  harshness  due 
to  the  latter,  and  does  not  increase  the  sulfates.  Acid  phosphates  of 
potash  are  left  in  the  wine  and  the  lime  is  deposited  as  neutral  lime 
tartrate.  Nothing  injurious  is  left  in  the  wine,  and  the  phosphates 
doubtless  aid  the  completion  of  the  fermentation.  It  has,  however,  the 
same  defect  of  being  unreliable,  as  its  action  is  very  variable  and  it  is 
impossible  to  foretell  the  effect  of  a  certain  dose. 


MANUFACTURE   OF    DRY   WINES    IN    HOT    COUNTRIES.  33 

CONTROL   OF   FERMENTATION. 
MODIFYING  THE  TEMPERATURE. 

All  the  fermentations,  good  and  bad,  to  which  must  or  wine  is  liable 
are  caused  by  micro-organisms  which  get  into  the  liquid  either  from  the 
outside  of  the  grapes  or  from  the  crushers,  casks,  etc.,  with  which  the 
liquid  comes  in  contact.  These  micro-organisms,  which  thus  get  into 
the  must,  consist  of  yeasts,  molds,  and  bacteria  of  a  very  great  number 
of  kinds.  Few  of  these  kinds,  however,  can  grow  in  the  must,  and  under 
the  best  conditions  of  wine-making  practically  none  grow  but  the  true 
wine-yeast.  A  perfectly  clean  or  pure  fermentation  is  one  in  which  no 
micro-organism  takes  part  except  the  true  wine-yeast.  This  is  the  ideal 
condition  toward  which  the  wine-maker's  efforts  should  tend.  It  is, 
however,  by  no  means  essential  for  the  production  of  good  wine  that 
this  condition  should  be  reached.  All  that  is  necessary  is  that  the  true 
wine-yeast  should  vastly  outnumber  all  the  others,  and  that  nothing 
should  interfere  with  its  healthy  and  complete  action.  In  the  finest 
chateau  wines,  molds  and  false  yeasts  occur  in  the  first  stages  of  fer- 
mentation, but  the  conditions  of  wine-making  are  such  that  they  have 
little  or  no  perceptible  effect  on  the  must  before  the  true  wine-yeast 
commences  its  action.  This  action  soon  overcomes  all  others  and,  if 
nothing  interferes  with  it,  the  wine  is  given  a  stability  which  makes  it 
a  simple  matter  to  prevent  all  ulterior  action  of  injurious  fermentative 
agents. 

The  main  problem  of  wine-making,  then,  after  we  have  obtained  the 
best  possible  raw  material,  is  to  produce  a  clean  fermentation.  This  is 
to  be  accomplished  in  one  or  both  of  two  ways:  (a)  by  establishing  con- 
ditions favorable  to  the  growth  of  wine-yeast  and  unfavorable  to  the 
growth  of  the  other  organisms;  and  (b)  by  eliminating  the  other  organ- 
isms and  having  as  little  present  as  possible  in  the  must  but  pure  wine- 
yeast.  One  of  the  most  essential  conditions  is  established  when  our 
raw  material  is  of  proper  composition,  that  is,  when  the  various  sub- 
stances in  the  grapes,  especially  the  acid  and  sugar,  are  in  the  proper 
proportion.  This  is  all  that  is  necessary  in  a  cool  climate  to  insure  a 
clean  fermentation  if  the  presence  of  too  many  unfavorable  fermentative 
organisms  is  prevented  by  ordinary  care  and  cleanliness.  In  a  hot 
region,  on  the  other  hand,  however  favorable  the  composition  of  the 
grapes  and  however  cleanly  the  methods  of  handling  them,  a  thorough, 
clean  fermentation  is  rarely  obtained  unless  we  control  other  condi- 
tions. The  principal  of  these  conditions  is  the  temperature.  The  use 
and  necessity  of  a  high  temperature  to  properly  extract  the  grapes  have 
already  been  pointed  out.  The  danger  of  high  temperatures  consists 
principally,  in  practice,  in  their  effect  on  the  fermentative  organisms. 

The  injurious  effects  of  too  much  heat  during  fermentation  are  of  two 

3— bul.  167 


34  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT    STATION. 

kinds,  which  should  be  carefully  distinguished.  In  the  first  place,  high 
temperatures  encourage  the  growth  of  the  bacteria  which  cause  most  of 
the  spoiling  of  wine.  In  the  second  place,  the  chemical  actions  which 
the  yeast  brings  about  in  the  must  at  a  high  temperature  are  different 
from  those  which  it  causes  at  a  low  temperature.  The  first  effects 
would  be  prevented  by  any  means  which  excluded  the  presence  of  bac- 
teria in  the  fermenting  must;  the  latter  are  dependent  only  on  the 
yeast.  It  is  possible  to  ferment  completely  all  the  sugar  in  any  ster- 
ilized must  which  does  not  contain  more  than  26%  at  any  temperature 
between  15c  C.  (59°  F.)  and  35°  C.  (95°  F.);  but  the  qualities  of  the  wine 
made  at  the  two  temperatures  will  be  very  different.  Leaving  out  of 
account  the  extractive  effects,  a  wine  fermented  near  the  lower  limit 
will  be  smoother,  fresher,  and  contain  more  alcohol  and  bouquet  than 
one  fermented  near  the  higher.  In  practice,  a  wine  fermented  at  the 
higher  temperature  may  be  more  valuable  on  account  of  the  greater 
color,  tannin,  and  body  it  contains,  if  these  latter  characteristics  are 
what  constitute  its  main  value. 

It  is  the  failure  to  properly  distinguish  between  these  two  effects  of 
heat  that  causes  the  wide  discrepancies  between  the  figures  given  by 
various  authorities  as  to  the  most  favorable  temperature  for  wine- 
making.  The  finest  Rhine  wines  are  kept  at  about  15°  C.  (59°F.)  during 
the  greater  part  of  the  fermentation,  while  in  Algeria  it  is  considered, 
by  most  wine-makers,  advisable  to  allow  the  temperature  to  rise  to 
35°  C.  (95°  F.).  In  the  former  case  the  most  valuable  characteristic  of 
the  wine  is  its  bouquet  and  aroma,  which  would  be  destroyed  at  high 
temperatures,  while  in  the  latter  the  color,  body,  and  tannin,  which 
constitute  the  main  value  of  the  wine,  would  not  be  sufficiently  extracted 
from  the  skins  at  a  lower  temperature.  In  the  Medoc  and  Burgundy 
districts  it  is  considered  desirable  to  keep  the  wine  during  fermentation 
at  between  25°  and  30°  C.  (77°  and  86°  F.).  This  is  low  enough  not  to 
destroy  either  the  freshness  or  the  bouquet,  and  high  enough  to  extract 
the  skins  sufficiently  with  the  thorough  stirring  and  long  maceration 
practiced  in  these  regions. 

In  hot  regions,  like  those  of  Algeria,  and  most  parts  of  California,  all 
considerations  give  way  to  the  necessity  of  finding  means  of  making 
a  sound  wine,  which  is  the  first  essential.  For  this  purpose  the  temper- 
ature will  in  these  regions  nearly  always  rise  too  high  unless  means 
are  taken  to  prevent  it. 

COOLING    DEVICES    ( PHYSICAL) . 

The  temperature  to  which  the  fermenting  grapes  rise  is  determined  by 
the  heat  they  contain  when  crushed,  plus  the  heat  generated  by  fermen- 
tation and  minus  that  lost  during  the  process  by  radiation  and  conduc- 
tion.    The  warmer  the  grapes  and  tin;  more  sugar  they  contain,  therefore, 


MANUFACTURE   OF    DRY   WINES   IN    HOT    COUNTRIES.  35 

the  higher  the  temperature  will  rise.  The  smaller  the  fermenting  mass, 
the  cooler  the  air,  the  greater  the  conductivity  of  the  vats,  and  the 
slower  the  fermentation,  the  less  the  temperature  will  rise.  Gathering 
the  grapes  only  in  the  early  morning,  or  leaving  those  gathered  in  the 
hot  part  of  the  day  exposed  to  the  night  air  before  crushing,  is  a  very 
effective  way  of  controlling  the  temperature  in  small  cellars.  In  large 
cellars  this  is  impossible,  owing  not  only  to  the  practical  difficulties  of 
finding  receptacles  for  the  grapes,  but  to  the  fact  that  however  cold  the 
grapes  are  crushed,  the  temperature  of  large  masses  will  rise  above  the 
danger  point  unless  the  heat  of  fermentation  is  eliminated  in  some 
way.  Professor  Bouffard*  has  shown  experimentally  that  180  grams  of 
sugar  give  out  at  least  23.5  calories  during  fermentation.  This  means 
that  22%  of  sugar  in  a  fermenting  must  is  capable  of  generating  enough 
heat  to  raise  the  temperature  about  90°  F.  If  none  of  the  heat  were 
lost,  therefore,  a  must  containing  22%  of  sugar  and  commencing  fer- 
mentation at  a  temperature  of  60°  F.  would  reach  100°  F.  and  "  stick  " 
while  it  still  contained  12%  of  sugar.  In  practice  some  of  this  heat  is 
always  lost,  but  with  hot  weather  and  large  vats  it  shows  that  it  is 
possible  for  the  fermenting  must  to  "  stick"  however  low  in  sugar-con- 
tents it  may  be,  and  however  cool  the  grapes  are  when  crushed.  Cool- 
ing the  grapes  or  must,  therefore,  is  only  a  partial  remedy,  and  quite 
insufficient  to  insure  thorough  fermentation  unless  supplemented  by 
some  other  means. 

Aids  to  Radiation. — Any  means  which  promotes  the  radiation  of  heat 
from  the  fermenting  mass  tends  to  moderate  the  rise  in  temperature. 
One  such  means  is  the  use  of  small  fermenting  vats.  The  smaller  the  vat 
the  greater  will  be  the  surface  from  which  heat  radiates  in  proportion 
to  the  volume  of  the  mass  of  grapes.  For  example,  a  fermenting  vat  of 
the  ordinary  form,  containing  100  gallons,  will  have  a  radiating  surface, 
reckoning  the  top,  bottom,  and  sides,  of  about  31  square  feet,  or  .311 
square  foot  for  every  gallon  of  crushed  grapes  it  contains,  while  one  of 
1,000  gallons  will  have  about  144  square  feet,  or  .145  square  foot  per 
gallon,  and  one  of  10,000  gallons  about  670  square  feet,  or  only  .067 
square  foot  for  every  gallon.  How  little  the  radiation  from  even  the 
smallest  vats  used  in  commercial  cellars  can  be  depended  on  to  keep 
the  temperature  below  the  danger  point  is  familiar  to  every  practical 
wine-maker.  Numerous  experiments  made  at  Berkeley  make  this  point 
certain. f  To  quote  one:  Two  hundred  pounds  (about  25  gallons)  of 
crushed  grapes  were  placed  in  a  small  vat  and  allowed  to  ferment  in 
the  ordinary  way  with  three  stirrings  daily.  The  temperature  of  the 
room  varied  between  72°  and  75°  F.,  and  the  grapes  showed  63°  F.  when 

*  "  Progres  Agricole  et  Viticole,"  vol.  24,  p.  345. 

t  E.  W.  Hilgard:  "Methods  of  Fermentation,"  p.  15.  See  exp.  792,  Report  of  Agri- 
cultural Experiment  Station,  Berkeley,  1888. 


36  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 

crushed.  Notwithstanding  these  favorable  conditions  of  cool  grapes  and 
small  vat,  the  temperature  rose  to  94°  F.  during  fermentation.  The 
grapes  contained  about  24%  of  sugar,  which,  according  to  Bouffard's 
tests,  would  produce  enough  heat  in  fermenting  to  raise  the  grapes  from 
their  initial  temperature  of  63°  F.  to  about  120°  F.  Radiation  thus  got 
rid  of  24°  F.  by  the  time  the  fermentation  reached  its  maximum.  In  a 
10,000-gallon  vat  radiation  could  have  removed,  providing  all  other 
conditions  were  the  same,  only  one-seventh  of  this  amount,  and  even  in 
a  1,000-gallon  vat  only  three-tenths,  which  would  not  have  been  enough 
to  prevent  arrest  of  fermentation  long  before  the  sugar  was  all  gone. 

Vats  smaller  than  1,000  gallons  are  not  practicable,  even  in  small 
cellars,  so  that  control  of  temperature  by  diminishing  the  size  of  the 
vats  is  incomplete  and  impracticable  for  California  conditions.  The 
same  may  be  said  of  vats  of  special  forms.  Very  high,  narrow  vats 
such  as  are  used  by  brewers,  or  very  wide,  shallow  vats  as  used  in  some 
wineries,  radiate  more  heat  than  vats  of  the  ordinary  form:  but  the 
difference  is  so  little  under  ordinary  conditions  that  it  can  not  be 
depended  upon  to  prevent  "  sticking."  A  3,000-gallon  vat  with  a  depth 
of  6  feet  presents  a  radiating  surface  of  about  313  square  feet,  while  one 
of  the  same  capacity  with  a  depth  of  only  3  feet  has  388  feet  of  radiating 
surface.  The  difference  in  radiated  heat  is  no  doubt  greater  than  is 
indicated  by  these  figures,  as  most  of  the  radiation  takes  place  from  the 
upper  surface  of  the  pomace,  which  in  the  shallow  vat  will  have  an  area 
of  about  125  square  feet,  and  in  the  deep  vat  only  about  55  square  feet. 
The  difference  is  not  enough,  however,  to  keep  the  temperature  -  suffi- 
ciently low,  except  in  small  vats  and  in  cool  weather. 

Various  forms  of  gratings  for  submerging  or  dividing  the  pomace  have 
been  in  limited  use  as  aids  to  cool  fermentation.  They  are  attempts  to 
counteract  the  tendency  of  the  pomace  to  rise  to  the  top  and  form  a 
semi-dry  "cap"  where  the  heat  becomes  excessive,  even  when  the  must 
below  keeps  comparatively  cool.  Some  of  these  gratings  keep  the  pomace 
near  the  bottom  of  the  vat,  where  it  can  not  become  hotter  than  the 
must  above,  owing  to  the  tendency  of  the  cooler  must  to  sink  on  account 
of  its  greater  specific  gravity.  Others  are  arranged  with  the  object  of 
promoting  the  continual  circulation  of  the  must  through  the  cap,  and 
thus  preventing  any  part  becoming  hotter  than  the  rest.  These  appli- 
ances are  all  very  troublesome  to  use,  and  at  the  best  are  only  palliatives. 
Frequent  stirring  (foulage)  of  the  fermenting  mass  is  almost  equally 
effective  and  is  more  easily  applied. 

An  ingenious  method  of  cooling,  at  one  time  discussed  a  good  deal  and 
tested  to  some  extent  in  Algeria,  is  that  of  Toutee.  It  is  based  on  an 
attempt  to  increase;  the  heat  radiation  from  the  sides  of  the  vats.  With 
the  ordinary  wooden  vat  and  still  more  with  stone  or  concrete  vats, 
there  is  very  little  radiation,  except  from  the  top  of  the  grapes  exposed 


MANUFACTURE   OP   DRY   WINES   IN   HOT    COUNTRIES.  37 

to  the  air.  Toutee  constructed  vats  of  metal,  where  the  radiation  from 
the  sides  was  so  much  increased  that,  except  in  warm  weather,  white 
must  was  kept  sufficiently  cool  in  3,000-gallon  vats.  With  red  grapes, 
owing  to  the  presence  of  the  pomace,  the  effect  was  less,  unless  continued 
stirring  or  pumping-over  was  practiced.  A  vital  defect  of  the  system 
was  its  cost  and  the  necessity  of  replacing  the  vats  on  hand. 

"Pumping-over"  is  an  operation  resorted  to  very  frequently  in  Algeria 
and  France  as  in  California  for  promoting  a  dilatory  fermentation.  Its 
rationale  is  not  always,  however,  well  understood.  It  is  not  properly  a 
method  of  cooling.  In  fact,  it  generally  has  the  other  effect.  The  only 
case  in  which  it  really  cools  the  must  is  near  the  end  of  the  fermenta- 
tion, when  it  is  desirable  to  prevent  cooling  in  order  not  to  check  the 
action  of  the  yeast.  It  is  often,  nevertheless,  very  effective  in  producing 
a  thorough  fermentation.  This  it  does,  not  by  cooling  the  must,  but  by 
providing  the  yeast  with  an  abundance  of  oxygen,  which  strengthens 
and  stimulates  it  and  enables  it  to  attack  the  sugar  more  forcibly.  It 
is  very  effective  and  useful  at  the  beginning  of  the  fermentation  in  cool 
weather,  or  when  real  cooling  means  are  applied  as  well.  In  hot  weather 
it  is  more  likely  to  increase  the  trouble,  and  toward  the  end  of  fermenta- 
tion it  entails  a  loss  of  alcohol  and  a  vapid  taste,  which  may  more  than 
offset  any  benefit  derived. 

Attemperators  and  Refrigerators. — The  failure,  in  the  majority  of  cases, 
of  all  the  methods  previously  discussed,  long  ago  led  the  wine-makers 
of  Algeria  to  look  for  some  more  effective  and  reliable  method  of  con- 
trolling the  temperature.  This  they  have  found,  after  many  trials,  in 
two  or  three  forms  of  machines  known  by  the  above  names.  An  attem- 
perator  is  an  appliance — usually  a  long  spiral  tube — which  is  placed 
in  the  fermenting-vat  and  through  which  water  or  other  cooling  liquid 
is  run.  A  refrigerator  is  an  appliance — also  usually  a  spiral  tube — 
outside  the  vat,  through  which  the  wine  is  run,  and  which  is  cooled  by 
a  cold  liquid  on  the  outside.  Innumerable  forms  of  both  classes  of 
machines  have  been  tested,  but  only  a  few  have  come  into  general  use. 

A  very  efficient  form  of  attemperator  is  that  used  at  the  Government 
wine  cellar  of  Constantia  in  Cape  Colony  and  in  some  Australian 
cellars. 

Fig.  2  will  make  clear  the  principles  involved.  Each  vat  is  fur- 
nished with  a  grating  by  which  the  pomace  is  kept  submerged  several 
inches  below  the  must,  and  with  a  small  pump  for  bringing  the  must 
from  the  bottom  to  the  top.  When  the  temperature  rises  to  the  point 
which  it  is  not  desired  to  exceed,  a  copper  coil  is  placed  in  the  must 
above  the  grating  and  attached  to  a  water  tap.  Cool  water  running 
through  this  coil  soon  brings  down  the  temperature  of  the  supernatant 
must.  In  the  meanwhile  the  pump,  which  is  attached  to  a  shaft  which 
4— bul.  167 


38 


UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 


works  all  the  small  vat  pumps,  is  started,  and  a  continuous  but  slow- 
flow  of  liquid  is  established,  which  is  cooled  as  it  comes  in  contact  with 
the  coil  on  top  and  cools  the  pomace  as  it  passes  through.  This 
arrangement  gives  very  perfect  control  of  the  fermentation,  with  compara- 
tively little  labor.  In  vats  of  one  or  two  thousand  gallons  the  tempera- 
ture can  be  kept  at  any  point  desired,  and  the  extraction  of  the  pomace 
can  be  increased  or  diminished  very  considerably  by  the  more  or  less 
constant  working  of  the  vat  pumps.  Whether  the  control  of  tempera- 
ture or  the  extraction  of  the  pomace  would  be  as  complete  in  large  vats 
where  the  pomace  cap  beneath  the  grating  was  very  thick,  is  doubtful. 


Fig.  2.    Cooling  device  for  fermenting-vat. 

The  method,  however,  is  excellent  in  small  or  medium-sized  cellars, 
where  the  object  is  to  make  wine  of  high  quality.  Its  principal  objec- 
tion is  the  initial  expense. 

Cheaper  attemperators  have  been  made  consisting  simply  of  coils  of 
copper  or  varnished  galvanized  iron  piping  placed  around  the  inside 
walls  or  in  various  other  positions  in  the  vats.  They  are  all  efficient 
enough  for  the  cooling  of  white  wine  where  there  is  no  solid  matter 
present,  but  are  quite  inadequate  for  the  case  of  red  wine,  and  fail  almost 
completely  to  prevent  undue  heating  in  the  cap,  except  in  small  vats 
where  continuous  stirring  can  be  practiced. 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES. 


39 


Refrigerators. — Appliances  of  many  forms  arranged  for  the  cooling  of 
the  fermenting  must  outside  the  vat  have  been  devised  and  tested. 
Only  two  types  are  in  extensive  use  at  the  present  time,  however.  The 
more  common  of  these  is  that  originated  by  Muntz  and  Rousseau,* 
which  is  made  by  several  manufacturers  of  cellar  appliances.  It  con- 
sists of  a  series  of  horizontal,  superposed  copper  tubes,  connected  in 
such  a  way  that  the  warm  must  enters  at  the  bottom  and  emerges  at  the 
top.  The  cooling  is  obtained  by  causing  water  to  drop  or  flow  over  the 
tubes  from  top  to  bottom.  This  form  (Fig.  3)  is  useful  especially  where 
water  is  scarce,  and  is  the  type  used  almost  exclusively  in  Algeria. 
There  is  probably  not  a  single  large  cellar  in  Algeria,  Oran,  or  Constan- 


ts*"' 

Fig.  3.    Algerian  type  of  refrigerator. 

tine  which  does  not  possess  one  or  more  of  these  machines,  and  by  their 
use  the  production  of  a  sound,  completely  fermented  wine  has  become 
possible  in  all  cases. 

The  amount  of  cooling  necessary  is  indicated  by  the  following  example: 

Grapes  containing  20%  of  Fermentable  Sugar. 

Temperature  of  grapes  when  crushed 20°  C. 

fHeat  liberated  by  fermentation  of  20%  of  sugar 26°  C. 

Total  temperature  units 46°  C. 

In  order,  then,  to  prevent  the  temperature  of  the  fermenting  must  from 
rising  above  35°  C,  it  is  necessary  to  remove  11°  C,  or  approximately 
11  calories.     That  is  to  say,  when  the  temperature  reaches  35°  C,  if  it  is 

*  See  Bull.  117,  Calif.  Agr.  Exp.  Station. 

t  Calculated  by  using  Prof.  Bouffard's  figure  of  1.3  calories  for  each  per  cent  of  sugar. 


40 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


cooled  to  24°  C.  the  sugar  will  have   all  disappeared  by  the  time  it 
reaches  35°  C.  again,  as  shown  by  the  following  table: 


Temperature. 

Degrees  of  Temperature. 

Per  Cent  of  Sugar. 

Gained. 

Removed. 

Removed. 

Remaining. 

20°       -    

20.0 

35°                 ~   

15 

11.5 

8  5 

24°  cooled..-  -       .     

11 

35°                         

11 

20.0 

00 

This  supposes  that  no  heat  is  abstracted  except  that  taken  by  the 
cooling  machine.  In  practice,  even  in  large  concrete  vats,  a  certain 
amount  of  heat  is  lost  by  radiation,  so  in  the  case  above  it  would  not 
be  necessary  to  remove  quite  11  calories.  In  California,  with  our  sweeter 
grapes  and  hotter  weather,  it  would  be  necessary  to  remove  more  heat 
than  in  Algeria  and  generally  to  cool  twice.  The  following  may  be 
considered  an  average  example: 

Grapes  containing  22  %  of  Fermentable  Sugar. 

Temperature  of  grapes  when  crushed . 70.0°  F. 

Heat  liberated  by  22%  of  sugar  r 51.7°  F. 

Total  temperature  units  121.7°  F. 

In  order  to  prevent  the  temperature  rising  above  95°  F.  it  would  be 
necessary  to  remove  heat  equivalent  to  26.7°  F.  or,  allowing  for  a  certain 
amount  of  loss  by  radiation  and  conduction,  the  cooler  would  have  to 
remove  about  20°  F.  It  would  be  easier  and  probably  more  desirable 
to  remove  this  by  two  coolings  of  10°  F.  each  than  by  a  single  one  of 
20°  F.;  easier,  because  it  requires  less  time  and  less  water  of  a  given 
temperature  to  cool  must  from  95°  to  85°  than  from  85°  to  75°,  and 
probably  more  desirable,  as  some  observers  claim  that  too  much  cooling 
at  one  time  delays  fermentation.  The  relation  of  the  temperature  with 
the  disappearance  of  the  sugar  would  then  be  somewhat  as  follows: 


Degrees  of  Temperature. 

Per  Cent  of  Sugar. 

Temperature  of  Wine. 

Gained. 

Removed. 

Removed. 

Remaining. 

70°               

0 
25 

0 
........ 

0 
12 

22 

95°                              

10 

85°  (first  cooling)    .         - 

<)5°                   .  . 

10 

17 

5 

85°  (second  cooling) 

10 

05° 

10 

22 

0 

These  figures  in  the  temperature  columns  of  the  foregoing  tables  must 
not  be  understood  to  represent  the  actual  temperatures  found  in  prac- 
tice.    At  no  time  would  there  be  a  fall  of  temperature  from  95°  to  85°  F. 


MANUFACTURE   OF    DRY   WINES   IN    HOT    COUNTRIES.  41 

of  the  whole  mass  of  fermenting  grapes.  This  difference  of  10  degrees 
simply  represents  the  amount  of  heat  which  it  is  necessary  to  remove 
during  one  cooling,  and  is  useful  in  indicating  the  amount  and  the 
temperature  of  the  water  needed.  While  the  cooling  is  going  on,  fer- 
mentation and  the  production  of  heat  continue,  so  that  though  the  must 
passing  through  the  cooler  may  be  reduced  10  degrees  or  more,  the 
whole  mass  in  the  vat  will  be  reduced  very  much  less  or  even  not  at  all. 
The  good  effect  consists,  in  the  latter  case,  not  in  cooling  the  fermenting 
mass,  but  in  preventing  its  temperature  from  rising  any  higher. 

A  description  of  the  common  Algerian  practice  in  cooling  will  make 
this  clearer.  As  a  rule,  the  fermenting-vats  are  made  of  such  a  size 
that  two  of  them  will  contain  exactly  the  amount  of  grapes  gathered 
in  one  day.  One  is  filled  in  the  morning  and  another  in  the  afternoon. 
When  the  temperature  of  the  first  vat  reaches  35°  C.  the  faucet  at  the 
bottom  is  attached  to  a  pump  and  the  hot  must  passed  slowly  through 
the  cooler  and  back  into  the  vat  again.  The  must  as  it  leaves  the 
cooler  may  have  a  temperature  of  25°  C.  to  30°  C,  but  it  is  fermenting 
and  producing  heat  meanwhile  as  are  the  other  contents  of  the  vat,  so 
that  there  may  be  very  little  if  any  apparent  reduction  of  temperature 
in  the  vat.  The  sugar,  however,  is  disappearing,  until  a  time  comes 
when,  though  the  temperature  of  the  vat  may  still  be  nearly  35°  C, 
there  is  not  enough  sugar  left  in  the  must  to  heat  it  above  that  point. 
In  fact,  the  usual  plan  in  Algeria  is  to  start  pumping  through  the 
cooler  as  soon  as  the  must  reaches  35°  C,  and  to  continue  this  pump- 
ing until  the  fermentation  is  practically  finished,  that  is,  until  only  2% 
to  3%  of  sugar  is  left.  If  the  temperature  is  then,  say,  34°  C.  and  has 
never  exceeded  35°  C,  there  is  no  danger  of  the  vat  "sticking."  This 
pumping  through  the  cooler  occupies  eight  or  twelve  hours  for  each  vat, 
and  is  kept  up  night  and  day.  This  explains  the  arrangement  of  hav- 
ing two  vats  filled  per  day.  One  is  cooled  at  night  and  the  other  during 
the  day.  Every  vat  is  cooled,  and  cooled  but  once.  When  the  weather 
is  warm  and  the  grapes  very  sweet,  the  wine  is  kept  going  through  the 
cooler  for  a  longer  time.  On  the  other  hand,  cool  weather  and  grapes 
of  low  sugar-content  necessitate  less  time.  The  size  of  the  vats,  the 
size  of  the  cooler,  and  the  amount  of  water  should  be  so  calculated  that 
twelve  hours'  pumping  in  the  hottest  weather  with  the  sweetest  grapes 
expected  will  remove  the  necessary  amount  of  heat  from  half  the  grapes 
crushed  in  one  day.  In  hot  weather,  when  the  grapes  are  warm  when 
crushed,  it  will  be  necessary  to  cool  twice;  but  the  total  time  of  both 
coolings  should  never  exceed  the  twelve  hours,  or  an  extra  machine 
should  be  kept  in  reserve  for  exceptionally  hot  weather. 

In  order  to  show  what  a  cooler  of  this  type  may  be  expected  to  do 
under  California  conditions,  the  following  figures  have  been  calculated 
on  the  basis  of  actual  experiments  made.*     The  estimate  has  been 

*  "  Revue  de  Viticulture,"  vol.  7,  p.  365. 


42  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

made  for  a  cellar  receiving  a  maximum  of   100  tons   a   day  in  hot 
weather.*     In  cool  weather  more  could  be  handled: 

Cooling  by  Miintz  and  Rousseau1  s  Machine. 
(Average  case.) 

Grapes  containing  22%  of  sugar,  capable  of  developing 51.7°  F. 

Temperature  of  grapes  at  crushing 70.0 

Total  degrees  of  temperature '. 121.7 

Maximum  temperature  desired 90.0 

Number  of  degrees  necessary  to  be  removed 31.7 

Less  6.7°  F.  from  radiation 25.0 

Temperature  of  water 65.0 

(If  the  must  is  cooled  to  77^°  F.  as  soon  as  it  reaches  90°  F.  it  would  require 
two  coolings  to  remove  the  necessary  25  degrees.) 

Wine  to  cool  in  20  hours 24,000  gallons 

Water  required 48,000  gallons 

Machines  needed,  1.    (Capacity  of  M.  &  R.  machine,  2,400  gallons  per  hour.) 

If  the  grapes  contained  24%  of  sugar  and  their  temperature  at  crush- 
ing was  80°  F.  and  that  of  the  water  available  70°  F.,  which  is  an  extreme 
case,  two  machines  would  be  necessary  and  twice  the  amount  of  water. 
The  cost  of  the  water  is  merely  nominal  if  the  cellar  is  near  an  irri- 
gating ditch.  Recent  investigations  of  pumping  plants  in  practical  use 
in  irrigation  show  that  on  the  average  300,000  gallons  can  be  raised  10 
feet  for  about  $l.f 

For  a  cellar  of  the  size  supposed,  viz:  one  crushing  about  100  tons 
of  grapes  per  day,  two  coolers  would  be  necessary,  of  the  capacity  of 
Miintz  and  Rousseau's  largest  size  and  an  available  supply  of  about 
100,000  gallons  of  water  per  day,  the  temperature  of  which  should  never 
exceed  70°  F.  This  would  make  it  possible  to  prevent  the  wine  ever 
surpassing  90°  F.,  even  in  the  hottest  weather,  and  under  average  con- 
ditions not  more  than  half  the  water  and  only  one  machine  would  be 
used. 

Most  of  the  large  cellars  of  California  are  situated  where  they  can 
obtain  an  abundant  supply  of  water  by  pumping.  This  is  especially 
true  in  the  hotter  regions,  where  irrigation  is  practiced.  In  this  we  have 
a  great  advantage  over  Algeria,  where  water  is  very  frequently  scarce. 
The  various  ingenious  devices  invented  in  Algeria  for  cooling  the  water 
before  using  would  be  of  little  use  here,  because  it  would  hardly  ever  be 
necessary  to  use  the  same  water  twice,  and  cool  water  can  be  obtained 
in  nearly  all  cases.  Regular  observations  made  by  the  Irrigation 
Department  of  the  University  of  California  show  that  the  temperature 
of  the  main  irrigating  canals  in  the  San  Joaquin  Valley  during  the 
wine-making  season  varies  between  60°  and  70°  F.,  which  is  quite  cool 
enough  for  the  purpose. 

*  Newer  forms  of  this  type  of  cooler  are  even  more  efficient.  See  "  Progres  Agricole 
et  Viticole,"  vol.  30,  p.  19. 

t  S.  Fortier:  Circular  No.  50,  Office  of  Experiment  Stations,  Washington,  D.  C.,p.  10. 


MANUFACTURE   OF    DRY   WINES   IN   HOT    COUNTRIES. 


43 


Another  type  of  cooler  commonly  used  consists  of  a  long  copper  or 
galvanized  iron  pipe  laid  in  a  long  trough.  The  wine  is  pumped  through 
the  pipe  and  the  water  flows  in  the  trough  in  the  opposite  direction. 
The  device  is  simple,  easily  constructed  at  the  cellar,  and  is  not  costly. 
Its  main  defect  is  that  it  does  not  thoroughly  utilize  the  cooling  capacity 
of  the  water,  and  much  more  water  is  necessary.  Where  large  quanti- 
ties of  cool  water  are  available,  as  near  a  main  irrigating  canal,  it 
should  be  very  useful.     A  good  example  of  this  type  of  cooler  is  in 


Horizontal  section. 


w 

w 

<*> 

w 

0 

w 

W 

(?) 

Fig.  4. 


Vertical  section. 
Plan  and  section  of  a  wine  cooler  at  Le  Grand  Craboules,  Narbonne. 


operation  at  the  cellar  of  M.  Gaston  Gautier  near  Narbonne.  At  this 
cellar  is  made  about  500,000  gallons  of  wine  yearly.  The  trough  is 
made  of  six  walls  of  concrete  about  2  feet  high  and  4  inches  thick,  so 
arranged  that  the  water  flows  from  one  end  to  the  other  in  a  zigzag 
course.  The  galvanized  iron*  pipe  through  which  the  wine  runs  is  laid 
near  the  bottom  of  this  trough.     The  machine  is  said  to  run  all  the 

*The  pipe  should  be  tinned,  not  "galvanized,"  as  in  the  latter  case  the  zinc  covering 
will  be  quickly  corroded  by  the  acids  of  the  wine,  and  zinc  will  contaminate  the  wine. 


44  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 

season  without  cleaning,  and  remain  effective  to  the  end.  At  the 
end  of  the  season  the  wine  pipe  is  taken  apart  at  the  joints  and  cleaned. 
Such  a  cooler  as  this  could  be  very  easily  constructed  on  the  bank  of 
an  irrigating  canal,  or  the  piping  might  even  be  placed  directly  in  the 
canal. 

Ice.—  The  cooling  power  of  ice  might  be  used  very  effectively  to  pre- 
vent hot  fermentations,  if  it  could  be  obtained  cheaply  enough.  For 
white  wine,  it  is  easily  applied  by  placing  the  ice  in  a  tinned  copper 
tub  floating  on  top  of  the  must.  The  hottest  must  rises  to  the  top  and 
is  cooled  by  contact  with  the  tub  and  falls  to  the  bottom.  This  creates 
a  circulation  of  the  liquid,  which  maintains  a  uniform  temperature  in 
all  parts  of  the  vat.  For  fermenting  masses  of  crushed  grapes  this 
method  is  not  applicable.  In  this  case  the  ice  could  be  used  to  cool 
the  water  used  with  an  ordinary  refrigerator.  Five  pounds  of  ice  will 
reduce  100  gallons  of  must  about  one  degree  Fahrenheit.  To  reduce 
the  must  20  degrees  Fahrenheit,  as  in  the  case  instanced  on  page  40,  it 
would  require  over  one  pound  of  ice  for  every  gallon  of  must.  This  may 
be  taken  as  about  the  average  cooling  necessary,  so  that  for  every  ton  of 
grapes,  when  used  for  white  wine,  200  pounds  of  ice  would  be  needed, 
and  about  300  pounds  for  the  same  amount  of  grapes  when  used  for 
red  wine.  If  used  in  connection  with  a  water  refrigerator,  simply  to 
increase  the  coolness  of  the  water  where  only  warm  water  was  available, 
would  require  under  ordinary  conditions  about  the  same  amount. 

The  cost  of  cooling  for  ice  alone  would  amount  to  about  $1.50  per  ton 
of  grapes,  reckoning  ice  at  \  cent  per  pound,  which  is  about  1  cent  a 
gallon  for  the  wine  made.  This  is  much  more  than  the  whole  cost  of 
cooling,  including  labor,  where  it  is  possible  to  get  cool  water. 

The  method,  which  has  been  tested  in  California,  of  placing  the  ice 
directly  in  the  vat  with  the  idea  of  cooling  and  reducing  the  sugar  at  the 
same  time,  is  quite  inadmissible.  The  amount  of  ice  necessary  would 
introduce  far  too  much  water  into  the  must. 

CHEMICAL    COOLING    DEVICES. 

The  rise  of  temperature  in  a  vat  of  fermenting  grapes  is  due  to  the 
fact,  already  noted,  that  more  heat  is  produced  in  a  given  time  by  fer- 
mentation than  is  lost  by  radiation  and  conduction  in  the  same  time. 
The  heat  produced  is  limited  by  the  amount  of  fermentable  sugar 
present;  the  heat  lost,  by  the  time  of  fermentation.  If  the  fermentation 
is  rapid  the  excess  of  heat  produced,  over  that  lost  in  a  given  time,  will 
be  great,  and  the  rise  of  temperature  correspondingly  great.  If  on  the 
contrary  the  fermentation  is  slow,  the  excess  will  be  less  and  the  rise  of 
temperature  less.  If  the  fermentation  is  slow  enough,  the  heat  lost  may 
equal  the  heat  gained  and  no  rise  of  temperature  at  all  take  place. 


MANUFACTURE   OF    DRY   WINES   IN    HOT    COUNTRIES.  45 

Anything,  therefore,  which  retards  fermentation  will  lower  the  maxi- 
mum temperature  to  which  the  grapes  will  rise.  Various  substances 
may  be  added  to  the  must  which  have  this  effect  of  retarding  the  course 
of  fermentation.  The  only  one  which  has  come  into  practical  use  is 
sulfur ous  acid  in  some  form.  There  are  two  sources  of  this  acid 
which  are  at  present  extensively  used  in  wine-making.  When  sulfur  is 
burned  it  produces  sulfurous  acid  gas.  One  pound  of  sulfur  on  burn- 
ing yields  two  pounds  of  sulfurous  acid.  The  other  source  is  a  salt 
of  sulfurous  acid,  potassium  meta-bisulfite,  often  sold  commercially  under 
the  incorrect  name  of  potassium  sulfite.  When  this  salt  is  placed  in 
must  or  wine  it  is  broken  up  by  the  acids  in  the  wine,  and  yields  sul- 
furous acid  equal  to  57%  of  its  weight.  The  cost  of  the  sulfite  is  about 
23  cents  per  pound  in  France,  and  that  of  sulfur  less  than  2  cents.  As 
the  former  yields  only  one  fourth  as  much  sulfurous  acid  as  the  latter, 
the  cost  of  material  is  about  fifty  times  as  great.  The  difference  in  cost 
of  material  is  in  many  cases,  however,  counterbalanced  by  the  greater 
ease  with  which  the  sulfite  can  be  used. 

Sulfur. — The  fumes  of  burning  sulfur  have  long  been  used  in  the  man- 
ufacture of  white  wine  in  all  wine-making  countries.  The  finest  white 
wines  of  the  Rhine  and  Gironde  are  sulfured  in  this  way  very  heavily. 
Some  of  the  finest  of  the  former  contain  as  much  as  .20  per  mil.  to  .26  per 
mil.  of  sulfurous  acid.  Sauternes  and  Graves  of  the  Gironde  contain  sim- 
ilar amounts.  As  this  is  many  times  as  great  as  is  needed  for  controlling 
the  temperature,  and  as  practically  all  that  is  used  disappears  from  the 
wine  during  fermentation,  the  question  of  the  legality  or  wholesomeness 
of  the  practice  does  not  come  into  consideration  in  the  making  of  ordi- 
nary wine.  While  the  use  of  sulfurous  acid  has  other  advantages, 
especially  in  the  making  of  the  wines  mentioned,  in  ordinary  cases  one 
of  the  chief  benefits  is  the  moderation  of  the  rate  of  fermentation  and 
the  consequent  lower  temperature.  For  this  purpose  it  is  used  exten- 
sively in  southern  France  and  to  a  less  extent  in  Algeria.  To  give  an 
idea  of  the  moderation  of  temperature  realizable  in  the  fermentation  of 
red  wine,  the  following  example  may  be  given:*  Two  tests  were  made 
with  two  closed  vats  of  3,750  gallons  each.  One  vat  of  each  pair  was 
sulfured  and  both  filled  at  the  same  time  with  crushed  Carignane  grapes. 
In  Nos.  1  and  3,  2.2  pounds  of  sulfur  was  burned  before  filling.  When 
the  temperature  of  these  vats  reached  86°  F.  the  fumes  from  1.1  pounds 
of  sulfur  were  pumped  into  the  must.  Twenty-four  hours  later  this 
treatment  was  repeated.  Owing  to  the  method  of  introducing  the  sul- 
fur fumes  there  is  no  way  of  determining  how  much  the  must  absorbed, 
but  probably  not  more    than   10%   or  20%  of  the  amount  produced. 

*  "  Progres  Agricole  et  Viticole,"  vol.  29,  p.  536. 


46 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


Casks  Nos.  2  and  4  were  treated  in  every  way  the  same  as  Nos.  1  and  3. 
except  that  no  sulfur  was  used.     The  following  table  shows  the  results: 


Maximum 

Tempera-      Drawn  off  at 
ture 


Sugar 
Remaining. 


Alcohol  in 

Wine  at 
2  Months. 


Vat  No.  1,  sulfured  . 
Vat  No.  2,  no  sulfur 
Vat  No.  3,  sulfured  . 
Vat  No.  4,  no  sulfur 


93c 
102 

95 
104 


8  days 

9  days 
9  days 

10  days 


0 
2 
0 
2.5 


13.5 
13.0 
13.9 
13.3 


In  spite  of  the  retarding  effect  of  the  sulfurous  acid  the  fermentation 
in  the  sulfured  vats  finished  first.  Though  the  fermentation  in  the 
unsulfured  vats  was  most  rapid  at  first,  the  great  heat  developed 
stopped  the  action  of  the  yeast  before  all  the  sugar  had  disappeared,  so 
that  the  last  2%  of  sugar  required  several  weeks  to  ferment  out. 

The  alcohol  in  the  sulfured  wines  was  about  a  half  per  cent  higher 
than  in  the  others,  a  difference  due  in  great  part  probably  to  loss  from 
evaporation  while  pumping-over  the  latter  at  a  high  temperature. 

The  amount  of  sulfurous  acid  needed  to  delay  fermentation  is  indi- 
cated by  some  tests  made  by  Roos.*  Must  containing  .05  per  mil.  of 
sulfurous  acid  fermented  three  fourths  as  fast  as  without  any,  and  must 
containing  .1  per  mil.  fermented  less  than  one  half  as  fast.  These  fig- 
ures can  be  used  only  as  indications  of  where  to  commence  trials  in 
practice,  for  the  amount  necessary  will  depend  on  a  variety  of  condi- 
tions which  differ  for  every  cellar,  viz,  composition  of  must,  tempera- 
ture of  grapes  and  cellar,  amount  of  aeration,  kind  and  quantity  of 
yeast  present,  and  size  of  fermenting-vats.  The  amount  necessary 
depends  especially  on  the  amount  and  kind  of  yeast  present.  If  the 
sulfurous  acid  is  added  before  fermentation  starts,  a  small  amount 
delays  fermentation  considerably.  In  this  connection  Roos  f  gives  the 
following  figures  as  a  guide  to  the  use  of  sulfurous  acid  in  clearing 
white  must  before  fermentation  : 

To  delay  10-12  hours _ - 030  gram  per  liter. 

To  delay  18-24  hours 050  gram  per  liter. 

To  delay  48-60  hours .075  gram  per  liter. 

To  delay  5-6  days - 100  gram  per  liter. 

These  results  indicate  that  freshly  expressed  must,  to  which  has  been 
added  the  amounts  of  sulfurous  acid  mentioned,  will  not  show  percepti- 
ble fermentation  until  after  the  times  mentioned.  If  these  amounts  of 
the  acid  were  added  to  must  in  full  fermentation  they  would  not  stop 
the  action  of  the  yeast,  but  would  simply  diminish  its  rate,  as  in  the 
experiments  mentioned  on  page  45.  Therefore,  the  larger  the  amount 
of  yeast  present  the  more  sulfurous  acid  is  needed  to  delay  or  check  fer- 

*"Progres  Agricole  et  Viticole,"  vol.  29,  p.  225. 
t  Roos:  "  Industrie  Vinicole  Meridionale,"  p.  234. 


MANUFACTURE   OF   DRY   WINES   IN   HOT   COUNTRIES.  47 

mentation.  The  kind  of  yeast  also  influences  the  result.  Some  yeasts 
are  much  more  sensitive  to  the  action  of  the  acid  than  others.  Part  of 
the  good  effect  of  a  preliminary  sulfuring  of  the  must  is  that  the  true 
wine-yeast  is  more  resistant  to  sulfurous  acid  than  most  of  the  other 
organisms  present,  and  musts  thus  treated  are  therefore  likely  to 
undergo  a  purer  fermentation.  Yeasts  may  even  be  selected  with  a 
special  resisting  power,  as  in  the  process  described  on  page  56. 

The  possibilities  of  cooling  by  the  use  of  sulfurous  acid  are  of  course 
limited  by  the  amount  of  possible  loss  of  heat  by  radiation.  In  warm 
cellars,  or  in  very  hot  weather,  the  temperature  will  run  up  too  high  in 
spite  of  sulfuring.  The  same  is  true  of  fermentations  in  large  vats.  The 
method  is,  therefore,  of  limited  use,  and  while  very  effective  in  small 
cellars  and  cool  climates  is  usually  insufficient  under  other  conditions. 

In  the  south  of  France  the  white  musts  are  always  treated  with  the 
fumes  of  burning  sulfur.  The  old  method  was  to  burn  a  certain  quan- 
tity of  sulfur  in  each  cask  before  introducing  the  must.  Now  the 
must  is  usually  passed  through  a  "sulfurizer"  and  then  pumped  into 
the  casks.  In  both  methods  there  is  great  uncertainty  as  to  how  much 
sulfur  fumes  are  absorbed.  In  the  first  method  only  a  portion  of  the 
fumes  are  taken  up  by  the  must,  the  remainder  being  expelled  with  the 
air  as  it  is  forced  out  of  the  cask  by  the  must.  The  difficulty  is  not  so 
great,  however,  in  practice  as  it  seems  a  priori. 

If  a  small  quantity  of  sulfur  is  burned,  nearly  all  the  fumes  are 
absorbed,  while  if  a  large  quantity  is  burned,  the  greater  part  escapes. 
Practical  tests,  under  ordinary  cellar  conditions,  show  that  if  all  the 
sulfur  possible  is  burned  in  a  small  cask,  the  must  when  introduced  in 
the  ordinary  way  through  a  hose  will  absorb  about  .1  per  mil.  of  sulfur- 
ous acid.  If  only  one  seventh  of  this  possible  amount  is  used  the  must 
will  absorb  .05  per  mil.,  or  half  as  much.  That  is,  if  we  burn  2.7  ounces 
of  sulfur  in  a  100-gallon  cask  it  will  have  only  twice  the  effect  of  burning 
.4  ounce.  The  amount  necessary  for  defecating  the  must  or  for  moder- 
ating the  heat  of  fermentation  lies  between  these  two  extremes  of  .1  per 
mil.  and  .05  per  mil.,  so  that  when  the  fermentations  take  place  in  small 
casks  the  rough  guess  of  the  cellarman  as  to  the  quantity  of  sulfur 
to  burn  is  usually  near  enough  for  practical  purposes.  With  large 
casks  this  is  not  always  true,  as  the  sulfur  fumes  are  absorbed  more 
completely.  The  absorption,  however,  is  not  complete  enough,  even  in 
this  case,  to  make  the  amount  of  sulfur  burned  a  sufficient  measure 
of  the  amount  of  sulfurous  acid  introduced  into  the  must. 

Many  ingenious  devices  exist  for  causing  the  must  to  absorb  all  the 
sulfur  fumes  produced  and  so  to  make  it  possible  to  introduce  an 
exact  amount.  These  devices  are  of  two  types:  In  one,  the  must  passes 
through  an  apparatus  placed  in  the  bunghole  of  the  cask,  so  constructed 
that  all  the  fumes  coming  out  of  the  cask  pass  through  the  incoming 


48 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION. 


must  and  are  therefore  absorbed.  In  the  other,  the  cask  is  filled  first 
and  the  sulfur  fumes  are  then  forced  into  the  cask  by  means  of  a  pump. 
Most  of  the  devices  of  the  first  type  are  cumbersome,  troublesome  to  put 
in  place,  and  are  little  used.     One  of  the   simplest  is  the  Brise-jet  of 


Fig.  5.    Brise-jet. 
R,  hose  for  entrance  of  wine;  T,  cover  of  manhole  to  which  is  attached  by  cords  a 
small  piece  of  wood,  P,  on  which  the  entering  wine  strikes  and  is  broken  up  into 
a  spray. 

Roos,  shown  in  Figs.  5  and  6.  By  means  of  this  simple  device  the  incom- 
ing stream  of  must  is  thoroughly  broken  up  into  a  spray,  and  tests 
show  that  only  from  1%  to  5%  of  the  sulfur  fumes  escape.  This  is  quite 
close  enough  for  practice.     It  can  not,  of  course,  be  used  except  where 


Fig.  6.     Illustrates  method  of  causing  absorption  of  sulfur  fumes  by  means  of  Brise-jet. 

F,  cask  containing  wine  or  must  to  be  sulfured  ;  A,  suction  hose  of  pump,  P ;  R,  delivery 

hose  conducting  wine  into  cask,  F,  in  which  sulfur  has  been  burned;  J,  Brise-jet. 

there  is  a  manhole  on  the  top  of  the  cask.  For  casks  with  only  a  bung- 
hole  on  top  a  long  tube  pierced  with  small  holes  may  be  adapted  to  the 
end  of  the  hose,  but  the  absorption  is  then  not  quite  so  complete. 

The  second  type  of  sulfurizer  is  exemplified  by  Fig.  7.  The  correct 
amount  of  sulfur  is  weighed  and  placed  in  an  iron  pan  beneath  a  cask 
from  which  one  head  has  been  removed.     The  suction  hose  of  a  pump 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES. 


49 


is  then  attached  to  the  bunghole  of  the  inverted  cask,  and  as  the  fumes 
are  given  off  they  are  driven  by  the  pump  into  the  must,  preferably 
through  a  hose  inserted  through  the  upper  bunghole.  This  method  is 
very  effective  for  introducing  large  quantities  of  sulfurous  acid,  but  is 
little  used.  The  hot  sulfur  fumes  are  apt  to  injure  the  hose  and  pump 
and  the  method  is  troublesome  to  use  in  large  cellars. 

The  sulfurizers  used  in  most  of  the  cellars  which  make  large  quanti- 
ties of  white  wine  are  similar  in  principle  to  the  one  shown  in  Fig.  8. 
An  examination  of  the  figure  (8)  will  make  clear  the  principle  of  the 
machine.  The  must  enters  by  the  hose  shown  at  the  upper  right-hand 
corner  of  the  figure,  flows  from  shelf  to  shelf  through  the  sulfuring  cham- 


Fig.  7.    Method  of  sulfuring  must  with  a  pump. 
M,  small  cask  with  one  head  removed,  serving  as  a  chamber  in  which  to  burn  the 
sulfur;  /,  /,  openings  for  entrance  of  air;  a,  r,  hose  through  which  the  sulfur 
fumes  are  forced  into  the  cask  of  wine  by  means  of  the  pump,  P. 


ber  into  a  reservoir  below.  The  sulfur  fumes  generated  in  the  stove 
slfown  at  the  lower  right-hand  corner  of  the  figure  enter  the  sulfuring 
chamber  near  the  bottom  and  take  a  zigzag  course  to  the  top  where  the 
current  of  air  which  carries  them  escapes  through  a  narrow  chimney. 
This  arrangement  insures  a  thorough  contact  between  the  must  and 
the  sulfur  fumes. 

The  sulfurous  acid  is  so  completely  absorbed  in  this  machine  that  there 
is  no  odor  of  burning  sulfur  at  the  opening  O  where  the  air  escapes. 
The  quantity  of  acid  absorbed  by  the  must  depends  on  the  amount  of 
sulfur  burned  and  the  rate  at  which  the  must  passes  through  the  appa- 
ratus.    It  is  possible  thus  to  approximate  a  certain  dose  in  sulfuring 


50 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION. 


the  must,  but  hardly  more  closely  than  by  the  old  method  of  burning 
the  sulfur  in  the  casks.  The  chief  merits  of  the  machine  are  saving  of 
labor  and  of  the  inconvenience  and  difficulty  of  burning  sulfur  in 
the  casks,  especially  when  they  are  large.  At  the  cellar  of  Villeroy, 
near  Cette,  where  1,000,000  gallons  of  white  wine  are  made  annually, 
all  the  must  is  sulfured  by  two  machines  constructed  on  this  principle. 
Any  of  these  methods  can  be  effectively  used  in  the  manufacture  of 
white  wine  where  the  dosing  of  the  sulfurous  acid  has  not  to  be  done 


Fig. 


Paul  sulfurizer. 


with  a  great  deal  of  exactness.  For  red  wine  they  are  very  imperfect, 
both  because  of  the  greater  difficulty  of  introducing  the  fumes  into  the 
crushed  grapes,  and  of  the  greater  need  for  precision  in  the  doses. 


Sulfites. — Sulfurous  acid  has  a  strong  bleaching  action  on  many  sub- 
stances, and  if  used  in  red  wine  tends  to  decolorize  it.  This  decoloriz- 
ing may  be  very  considerable  if  large  quantities  are  used,  as  is  shown 


MANUFACTURE   OP   DRY   WINES   IN   HOT   COUNTRIES.  51 

by  a  test  made  by  A.  Bouffard.*     Various  amounts  of  the  acid  were 
added  to  a  wine,  and  the  loss  noticed  as  follows  : 

Sulfurous  Acid  per  mil.  Loss  of  Color.  Loss  at  One  Month. 

•025 7% _. 3% 

.050  .._. 12% 6% 

.075  —  -  25%   20% 

.100  35%    30% 

The  second  column  shows  the  amount  of  color  lost  immediately  after 
sulfuring  when  compared  with  the  unsulfured  wine.  A  month  later  the 
difference  was  much  less,  especially  for  the  small  doses.  The  loss 
is  in  any  case,  however,  much  less  than  appears  at  first.  The  color  is 
not  all  destroyed  and  reappears  to  a  great  extent  as  the  sulfurous  acid 
disappears  from  the  wine  either  by  escaping  into  the  air  during  racking 
or  by  becoming  oxidized  to  sulfuric  acid,  or  by  forming  various  chemical 
combinations  with  substances  in  the  wine.  Moreover,  the  color  which 
is  left  is  more  brilliant  and  more  stable  than  that  in  an  unsulfured  wine. 
As  there  certainly  is  some  loss,  however,  especially  with  large  doses,  it  is 
necessary  to  use  no  more  than  is  absolutely  necessary  to  control  the 
temperature.  For  this  reason  potassium  meta-bisulfite  is  nearly  always 
used  in  preference  to  burning  sulfur  when  treating  grapes  and  must  for 
red  wine. 

The  bisulfite  is  very  easily  soluble,  and  may  be  dissolved  in  a  little  water 
which  is  added  to  the  grapes  gradually  as  they  are  crushed,  care  being- 
taken  to  distribute  it  well  in  all  parts  of  the  vat.  To  give  a  dose  of  .05 
per  mil.  of  sulfurous  acid  it  would  be  necessary  to  add  one-fifth  of  a 
pound  of  sulfite  to  every  ton  of  grapes.  This  would  cost  about  6  or  7 
cents.  The  sulfur  necessary  for  the  same  dose  would  cost  but  a  small 
fraction  of  a  cent,  but  would  be  more  troublesome  and  therefore  costly 
to  use,  besides  being  less  reliable. 

POSTPONEMENT    OF    FERMENTATION    UNTIL    WINTER. 

One  of  the  great  advantages  that  the  vineyards  of  the  high  Little  Atlas 
mountains  and  the  elevated  plateaus  of  Algeria  have  is  that  the  weather 
is  cool  during  the  fermenting  season.  This  is  due  partly  to  the  eleva- 
tion and  partly  to  the  late  ripening  of  the  grapes.  If  it  were  possible 
in  the  warmer  parts  to  prevent  fermentation  of  the  grapes  until  cool 
weather,  it  would  be  comparatively  easy  to  prevent  hot  fermentations. 
This  can,  in  fact,  be  done  by  treating  the  crushed  grapes  with  a  sufficient 
quantity  of  sulfite.  The  amount  necessary  depends  on  the  condition 
and  composition  of  the  grapes,  the  temperature  of  the  cellar,  and  the 
amount  of  yeast  present.  Clean,  acid  grapes  can  be  crushed  and  kept 
in  a  cool  cellar  for  months  by  adding  .5  mil.  of  sulfurous  acid  or  two 
pounds  of  sulfite  to  every  ton.  Grapes  with  little  acid  or  which  have 
commenced  to  ferment,  or  which   are    kept  in  a  warm  place,    would 

*Bouffard,  A.:  "  La  Casse  des  Vins,"  p.  24.     Montpellier,  1902. 


52  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

require  more.  The  smaller  amount,  however,  is  sufficient  to  injure  the 
color  of  red  grapes  considerably.  While  the  method  might  be  used 
for  white  grapes  or  must,  it  is  not  practicable  for  red  grapes  with  the 
present  arrangement  of  cellars,  as  it  would  necessitate  a  large  increase 
of  vats  or  other  cooperage. 

FERMENTATION    IN    A    COOL    LOCALITY. 

Large  quantities  of  grapes,  crushed  grapes  and  must,  are  transported 
from  the  south  of  Europe  to  the  north  for  wine-making  purposes.  This 
is  not  done,  however,  primarily  for  transferring  them  to  a  climate  more 
favorable  to  fermentation.  Grapes  are  sent  from  Italy  and  France  into 
Germany  for  the  purpose  of  supplementing  the  watery,  acid,  and  badly 
ripened  grapes  of  the  latter  country,  and  as  part  of  the  raw  material  of 
the  innumerable  vintages  fabricated  at  Hamburg  and  elsewhere.  Some 
of  these  grapes  are  transported  in  baskets,  barrels,  or  vats  as  they  are 
gathered,  but  the  greater  part  are  crushed  before  sending.  When  the 
distance  is  short  no  precautions  are  taken  to  prevent  fermentation,  but 
where  the  distance  is  over  two  or  three  days  the  crushed  grapes  and 
must  are  usually  preserved  with  sulfurous  acid.  The  amount  used  is 
about  .4  per  mil.,  or  about  1-J  pounds  of  sulfite  to  the  ton.  This  is  suffi- 
cient to  paralyze  all  the  yeast  present  and  to  prevent  any  danger  of 
fermentation  on  the  journey.  Fresh  must  from  sound  grapes  treated 
with  this  amount  will  usually  keep  for  several  months. 

There  is  no  doubt  that  if  the  grapes  of  the  San  Joaquin  Valley 
could  be  transported  to  the  Bay  Region  cheaply  enough,  there  would  be 
little  more  difficulty  in  fermenting  them  than  the  grapes  of  the  coast 
valleys.  This  is  proved  by  the  wines  made  at  the  California  Experiment 
Station  cellar  from  grapes  shipped  from  Tulare.  It  is  simply  a  question 
of  cost  and  shipping  facilities.  The  extra  freight  charges  would  be  con- 
siderable, as  the  weight  of  the  grapes  is  about  two-thirds  greater  than 
that  of  the  wine  they  make.  There  would,  besides,  be  the  cost  of  boxes 
or  other  receptacles.  In  parts  of  Italy  and  Algeria  crushed  grapes  are 
transported  in  specially  constructed  iron  tanks  on  railway  trucks.  Sul- 
fites could  be  used  only  for  white  wines,  on  account  of  the  large  amount 
necessary.  In  any  case  there  would  have  to  be  sufficient  guaranty 
that  the  grapes  would  not  be  more  than  two  days  from  the  time 
they  were  put  on  the  truck  to  the  time  they  were  placed  in  the  ferment- 
ing-vats. 

In  order  to  economize  in  freight  charges  many  attempts  were  for- 
merly made  to  concentrate  the  grapes  or  must  before  shipping.  No 
advance  seems  to  have  been  made,  however,  over  the  methods  of  Springh- 
miihl,  which  were  thoroughly  tested  in  California,  and  those  of  Favara 
in  Sicily.  The  method  is  fairly  successful  for  the  making  of  sweet 
wines,  but  these  can  be  made  as  well  or  better  in  hot  countries.     For 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES.  53 

dry  wines  the  concentrated  grapes  and  must  have  failed,  being  little,  if 
at  all,  better  than  dried  grapes  for  this  purpose. 

CONTROL  OF  THE  FERMENTATIVE  AGENTS. 

The  various  cooling  devices  just  discussed  act,  in  so  far  as  they 
prevent  imperfect  or  deleterious  fermentations,  by  controlling  the  fer- 
mentative agents.  That  is,  they  keep  the  fermenting  mass  at  a  tempera- 
ture favorable  to  the  true  wine-yeast  whose  action  we  want  to  assist, 
and  less  favorable  to  the  bacteria  and  other  injurious  organisms  whose 
action  we  want  to  hinder.  Cooling,  however,  only  hinders  the  growth 
of  the  latter,  but  in  no  case  completely  prevents  it.  Under  favorable  con- 
ditions this  action  is  so  slight  as  to  be  practically  inappreciable;  under 
less  favorable  conditions  the  freshness  and  bouquet  of  the  wine  may  be 
impaired,  or  in  extreme  cases  the  wine  spoiled.  These  are,  however, 
only  differences  in  degree.  If  we  could  find  some  means  of  absolutely 
excluding  all  organisms  from  the  must  except  the  true  wine-yeast,  we 
should  get  none  of  the  defects  due  to  injurious  secondary  fermentations 
under  any  conditions. 

Pure  Yeasts. — With  this  object  in  view  various  methods  have  been 
devised  for  sterilizing  the  grapes  and  must;  that  is,  of  freeing  them  from 
all  micro-organisms  of  any  kind,  and  subsequently  fermenting  them  by 
adding  a  pure  yeast.  A  pure  yeast  is  a  liquid  containing  no  micro- 
organisms but  yeast  cells  and  only  one  kind  of  yeast  cell.  For  about 
twenty  years,  extensive  laboratory  and  practical  tests  have  been  made 
with  these  methods,  but  there  is  still  wide  divergence  of  opinion  as  to 
their  merits.  There  is  perfect  unanimity  of  opinion  as  to  the  value  of 
eliminating  unfavorable  organisms,  but  on  the  value  of  the  use  of  pure 
yeast  there  is  much  difference  of  opinion.  On  one  side  it  is  claimed 
that  the  character  of  Chateau  Iquem  or  of  Clos  Vougeot  may  be  given 
to  the  wine  from  any  grape,  or  even  from  apples,  wherever  grown,  by 
the  use  of  a  pure  yeast  selected  from  the  vineyards  which  produce  these 
famous  wines.  Factories  are  in  existence  which  are  ready  to  supply 
yeasts  from  any  one  of  the  hundreds  or  thousands  of  famous  wines  of 
the  world,  with  the  implied  assurance  that  they  will  enable  any  wine- 
maker  to  produce  these  famous  wines  anywhere.  Much  of  this  is  no 
doubt  due  to  the  exaggeration  inseparable  from  advertising.  The  claims 
of  certain  laboratory  investigators  of  pure  yeasts,  however,  fall  little 
short  of  those  of  the  vendors  of  pure  yeast  for  wine-making,  and  are 
undoubtedly  in  many  cases  excessive  and  misleading.  At  all  events 
they  are  not  substantiated  by  results  in  practice,  or  by  the  work  of 
other  investigators.  On  the  other  hand,  it  is  an  equally  great  mistake 
to  suppose  that  the  purity  or  selection  of  the  yeast  has  no  effect  on  the 
wine.  The  comparative  purity  of  the  yeast  is  the  object  of  a  great  part 
5— bul.  167 


54  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

of  the  care  taken  wherever  good  wines  are  made,  and  there  is  no  doubt 
about  the  great  differences  which  exist  in  different  yeasts  and  in  their 
effects  on  the  wine. 

It  is  just  here  that  there  is  danger  in  the  use  of  absolutely  pure 
yeasts  prepared  by  modern  methods.  While  it  may  not  be  possible 
to  make  the  difference  between  a  "  Rommanee  Conti"  and  a  "  Chateau 
Lafitte"  wine  by  a  proper  selection  of  yeasts,  there  can  be  no  doubt 
whatever  that  it  is  possible  to  make  the  difference  between  a  good 
wine  and  a  bad  wine  from  the  same  material  according  as  we  use 
an  appropriate  yeast  or  an  inappropriate  one.  We  can  not  make  good 
wine  from  any  grapes  by  the  use  of  pure  beer-yeast,  bread-yeast,  or  any 
of  the  hundreds  of  yeasts  which  we  can  find  almost  anywhere.  More- 
over, it  is  quite  possible  to  select  from  grapes  pure  yeasts  which  have 
very  different  effects  on  the  wine  in  fermentation.  Some  pure  wine- 
yeasts  will  not  give  good  results  at  high  temperatures,  others  at  low; 
some  will  not  cause  the  fermentation  of  more  than  18%  of  sugar,  others 
can  ferment  26%  and  so  on.  If,  therefore,  we  use  pure  yeasts  we  must 
use  selected  pure  yeasts;  yeast  selected  and  tested  for  the  particular 
purpose  in  hand. 

Most  of  the  pure  yeasts  distributed  in  Germany  and  France  have 
been  properly  selected,  and  in  spite  of  the  exaggerated  claims  of 
the  makers,  usually  give  good  results  when  properly  used.  It  would, 
however,  be  quite  possible  to  completely  spoil  wine  by  the  use  of  a 
pure  yeast  not  properly  selected  for  the  particular  must  in  which 
it  is  placed.  This  is  no  doubt  the  reason  why  pure  yeasts  obtained 
from  the  regions  where  they  are  to  be  used  have  nearly  always  given 
better  results  than  yeast  imported  from  other  regions.  It  is  far  more 
likely  that  a  pure  yeast  separated  from  fermenting  Fresno  grapes  will 
prove  resistant  to  high  temperatures  and  capable  of  fermenting  very 
sweet  must,  than  one  separated  from  grapes  grown  on  the  Rhine.  The 
yeasts  which  exist  in  any  region  have  undoubtedly  been  subjected  for 
ages  to  a  process  of  natural  selection  which  has  fitted  them  for  the  con- 
ditions of  that  region.  Rhine  yeast  will,  therefore,  not  help  us  to  make 
Rhine  wine  in  Napa  County,  unless  we  can  get  grapes  whose  composi- 
tion approaches  those  of  the  Rhine,  and  can  imitate  the  temperature 
and  other  conditions  usual  in  the  Rheingau.* 

To  obtain  the  best  results  from  the  use  of  selected  yeasts  in  promoting 
a  thorough  fermentation  or  improving  the  wine  in  any  other  way,  a 
more  or  less  complete  sterilization  of  the  grapes  or  must  is  necessary. 
Very  numerous  trials  have  been  made,  with  this  object  in  view,  during 
the  last  twenty  years.  While  the  question  of  the  degree  of  improve- 
ment to  be  attained  by  the  use  of  selected  yeast  is  not  yet  settled,  the 

*See,  for  a  good  practical  example  of  this:— Report  of  Viticultural  Work,  College  of 
Agriculture,  Berkeley,  1887-93,  pp.  400-402. 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES.  55 

attempts  at  sterilization  have  brought  to  light  some  unforeseen  but  very 
important  facts  regarding  the  effect  of  the  methods  used  in  the  process 
of  wine-making. 

Attempts  have  been  made  to  free  must  from  fermentative  organisms 
in  various  ways ;  but  only  two,  so  far,  have  given  good  results  or  been 
adopted  in  practice.  These  are  sterilization  by  heat  and  sterilization 
with  sulfurous  acid. 

Twenty  years  ago  Louis  Marx  and  others  attempted  to  sterilize  musts 
by  heat  for  the  purpose  of  fermenting  them  with  pure  yeast.  The 
results,  while  promising,  were  not  completely  successful,  on  account  of 
the  cooked  and  "rancio"  taste  of  the  wines  made.  These  tastes  were 
due  to  the  imperfect  appliances  with  which  the  experiments  were  made. 
Later,  Rosenstiehl,  starting  from  the  known  facts,  that  the  cooked  or 
raisin  taste  was  due  to  heating  the  must  too  high  and  the  consequent 
caramelization  of  a  portion  of  the  sugar,  and  the  " rancio"  taste  due  to 
the  exposure  of  the  hot  must  to  the  oxygen  of  the  air,  invented  and 
patented  a  process  of  sterilizing  the  must  at  a  low  temperature  and  out 
of  contact  with  the  air.  The  first  defect  was  remedied  by  heating  the 
must  three  times  to  a  comparatively  low  temperature,  allowing  an 
interval  to  elapse  between  successive  heatings.  This  had  the  effect  of 
killing  all  germs  in  the  must  as  effectively  as  a  single  heating  to  a 
higher  temperature.  The  second  defect  was  avoided  by  keeping  the 
must  in  an  atmosphere  of  carbonic  acid  gas  during  the  heating. 

Rosenstiehl's  method,  while  effective,  was  slow,  and  required  compli- 
cated and  expensive  machinery.  Later  it  was  shown,  principally  by 
the  researches  of  Kayser  and  Barba  at  Nimes,  that  the  object  which 
Marx  and  Rosenstiehl  had  in  view,  the  absolute  sterilization  of  the 
must,  is  not  necessary  in  ordinary  wine-making;  and  further,  that  the 
absolute  exclusion  of  the  air  during  heating,  which  Rosenstiehl 
attempted,  is  also  unnecessary.  All  that  is  necessary  in  the  first  respect 
is  that  the  must  shall  be  "pasteurized";  that  is,  heated  to  such  an 
extent  that  all  active  germs  are  killed.  If  a  few  germs  in  the  latent 
or  spore  condition  are  left,  they  are  absolutely  innocuous,  as  they  can 
not  develop  in  time  to  do  any  harm.  Before  they  have  multiplied 
sufficiently,  the  wine  is  made  and  safe  from  their  attacks.  It  is  pos- 
sible, therefore,  to  eliminate  the  injurious  germs  sufficiently  by  one 
heating  to  a  temperature  too  low  to  caramelize  any  sugar. 

With  regard  to  the  "rancio,"  it  was  found  that  must  or  grapes  could 
be  heated  as  high  as  necessary  without  acquiring  this  taste,  if  the 
exposure  to  the  air  was  not  excessive  or  continued  for  too  long.  It  has 
lately  been  found  possible,  by  the  addition  of  a  little  sulfite  before 
heating,  to  almost  do  away  completely  with  any  danger  of  oxidation, 
even  with  considerable  contact  with  the  air,  and  at  the  same  time  to  get 
a  more  complete  sterilization  at  a  comparatively  low  temperature. 


56  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

Sulfiting. — A  method  which  promises  well  for  use  in  hot  climates  is 
one  devised  by  Martinand  and  Andrieu.  It  consists  of  adding  a  certain 
amount  of  bisulfite  of  potash  to  the  crushed  grapes  and  the  subsequent 
addition  of  selected  yeast.  The  addition  of  the  sulfite  is  sometimes 
spoken  of  as  a  "sterilization."  It  is  doubtful  if  the  amounts  used  are 
sufficient  to  actually  kill  all  germs  in  the  must,  but  they  are  sufficient 
to  prevent  them  from  developing  for  some  time ;  and  in  the  meanwhile 
the  selected  yeast  has  time  to  completely  take  possession  and  finish  the 
fermentation. 

There  are  three  ways  of  applying  this  method.  The  first  is  to  add 
sulfite  to  the  fermenting  grapes  in  two  or  three  doses,  and  is  practically 
identical  with  the  method  already  described  (see  page  46)  for  moderat- 
ing the  temperature  by  the  same  means.  The  other  two  methods  differ 
in  that  so  much  sulfite  is  used  that  ordinary  yeast  is  paralyzed  with  the 
other  germs.  For  this  reason  it  is  necessary  to  have  a  special  yeast 
which  is  capable  of  acting  in  the  presence  of  the  amount  of  sulfurous 
acid  introduced  into  the  wine.  Such  a  special  yeast  is  procured  by 
taking  any  good  strong  yeast  and  gradually  accustoming  it  to  grow  in 
the  presence  of  large  amounts  of  sulfurous  acid.  This  is  done  in  one  of 
two  ways.  The  way  recommended  by  Andrieu  is  to  fill  each  of  two  50- 
gallon  casks  one-third  full  of  must  sterilized  by  heating.  In  the  must 
in  one  cask  is  dissolved  .5  per  mil.  of  potassium  meta-bisulfite ;  that  is, 
1  ounce  to  15  gallons.  The  must  in  the  other  is  started  fermenting  by 
introducing  a  small  flask  full  of  pure  yeast.  As  soon  as  the  must  in 
the  second  cask  is  fermenting  well,  5  gallons  of  the  sulfited  must  from 
the  first  cask  is  poured  in.  This  will  check  fermentation  temporarily, 
but  in  a  few  hours  the  yeast  becomes  accustomed  to  the  sulfurous  acid 
and  fermentation  commences  again.  As  soon  as  fermentation  is  well 
reestablished  another  5  gallons  is  added ;  and  a  few  hours  later  the 
remainder  of  the  sulfited  must.  When  the  yeast  is  fermenting  well  after 
the  last  addition  of  sulfite,  it  is  ready  to  be  used  on  a  vat  of  grapes. 
The  grapes  as  they  come  from  the  crusher  are  sulfited  with  a  dose  of 
potassium  meta-bisulfite  equal  to  that  to  which  the  yeast  has  become 
accustomed,  i.  e.,  .25  per  mil.,  or  2  pounds  to  1,000  gallons  or  4  tons. 
This  is  sufficient  to  prevent  all  fermentation  except  that  of  the  added 
yeast.     A  pure  fermentation  is  thus  assured. 

The  other  method  is  to  train  the  yeast  in  the  fermenting-vat  itself. 
This  is  done  by  adding  a  pure  yeast  to  the  grapes  as  they  pass  into  the 
vat,  together  with  one-third  of  the  amount  of  sulfite  which  is  to  be  used, 
/'.  r>.,  two-thirds  of  a  pound  to  the  1,000  gallons.  This  is  enough  to 
retard  but  not  to  prevent  fermentation.  As  soon  as  fermentation  has  well 
started,  another  third  of  the  sulfite  is  added,  and  then  the  remainder 
when  renewed  fermentation  shows  that  the  effect  of  the  second  dose  has 
been  overcome. 


MANUFACTURE   OF   DRY   WINES   IN   HOT    COUNTRIES.  57 

All  these  methods  have  given  excellent  results  in  numerous  cases,  but 
the  second  and  third,  and  especially  the  second,  are  much  more  effective 
than  the  first. 

SUMMARY. 

METHODS  ADOPTED  IN  SOUTHERN  FRANCE  AND  ALGERIA. 

Modern  wine-making  in  these  regions  has  developed  along  different 
lines,  and  each  region  has  adopted  a  different  method  of  overcoming  the 
difficulties  connected  with  the  making  of  dry  wine  in  a  hot  climate. 

In  southern  France  these  difficulties  have  been  attacked  principally 
by  means  which  aim  at  making  the  raw  material  more  amenable  to  the 
conditions  and  methods  of  manufacture  which  exist  there.  The  suc- 
cessful production  of  dry  wines,  there,  depends  in  a  large  measure  on: 
(1)  the  planting  of  the  Aramon,  a  vine  which  produces  grapes  of  high 
acidity  and  low  sugar;  and  (2)  on  the  gathering  of  all  varieties  before 
they  are  perfectly  ripe.  While  the  trouble  of  incomplete  fermentations 
are  thus,  to  a  great  extent,  avoided  and  a  sound  wine  generally  made, 
the  result  is  not  altogether  satisfactory.  During  the  epoch  immediately 
following  the  destruction  of  most  of  the  vineyards  by  phylloxera  (1890- 
1899),  the  abundant  crops  of  thin,  watery  wine  were  very  profitable. 
Now,  when  the  supply  has  caught  up  to  or  passed  the  demand,  the 
price  obtained  for  the  wine  is  often  below  the  cost  of  production.  A 
very  large  proportion  of  the  Aramon  wines  can  not  be  marketed  without 
blending  with  heavier  wines,  and  in  years  when  the  crop  is  large  the 
price  falls  very  low.  In  1904  large  cellars  sold  their  crops  at  less  than 
6  cents  per  gallon,  and  the  average  price  was  probably  not  much  over  that 
figure.  The  wine  has  to  be  blended  with  Algerian  or  Spanish  wines, 
and  the  wine-merchant  can  afford  to  give  but  little  more  for  it  than  for 
piquettes  and  sugar  wines. 

In  Algeria  the  Southern  French  method  could  not  be  applied. 
There,  even  the  Aramon  often  attains  too  much  sugar  to  ferment  out 
completely  without  aid,  and  the  grapes  ripen  so  rapidly  in  the  hot 
autumn  that  it  is  impossible  to  gather  them  all  before  they  are  quite 
ripe.  Moreover,  in  the  hot  weather  which  is  often  experienced  during 
the  wine-making  season  in  Algeria,  grapes,  even  with  low  sugar-con- 
tent and  high  acidity,  may  fail  to  complete  their  fermentation.  Even 
if  the  Southern  French  method  were  possible,  it  would  be  impracticable 
in  Algeria,  where  it  would  always  be  unprofitable  to  produce  light 
blending  wines  in  competition  with  the  Midi.  The  demand  for  Alge- 
rian wines  is  based  on  their  capability  of  correcting  the  defects  o  (he 
Midi  wines,  and,  to  retain  their  market,  they  must  be  alcoholic  and  rich 
in  tannin,  color,  and  extract.  Some  means,  therefore,  had  to  be  found 
which  would  enable  the  wine-makers  to  ferment  Alicante  Bous  'net, 
Carignane,  and  similar  grapes  with  22%  to  26%  of  sugar.     The  only 


58  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

method  which  has  come  into  general  use  is  that  of  keeping  down  the  tem- 
perature with  cooling  machines.  This,  as  already  noted,  has  enabled 
them  to  produce  sound,  alcoholic  wines,  but  the  moderation  of  the  tem- 
perature has  entailed  a  loss  in  the  valuable  qualities  of  deep  color  and 
high  extract.  In  neither  France  nor  Algeria,  then,  are  the  present 
methods  of  manufacture  completely  satisfactory,  and  attempts  at  im- 
provement are  being  made  along  all  the  lines  discussed  in  this  report. 
On  the  whole,  however,  there  is  less  loss  from  spoiled  wine  there  than 
with  us,  and  a  consideration  of  the  methods  of  French  and  Algerian 
wine-makers  offers  many  suggestions  of  possible  improvements  in  our 
own  methods.  In  no  region,  however,  are  the  markets,  raw  materials, 
and  conditions  of  manufacture  identical  with  ours,  and  we  can  not, 
therefore,  copy  exactly  any  methods  however  successful  elsewhere. 
It  is  impossible,  moreover,  to  point  out  any  method  or  group  of 
methods  that  can  be  adopted  here  with  absolute  certainty  of 
success  in  all  regions.  It  is  possible,  however,  to  point  out  certain 
methods  which,  if  adopted,  will  certainly  result  in  great  improvement 
in  many  of  our  wines.  The  conditions  of  soil,  climate  and  grape  vari- 
eties in  Algeria  resemble  ours  much  more  than  do  those  of  southern 
France.  The  following  short  description  of  the  most  approved  method 
of  vinification  in  Algeria  should  be  of  interest.  It  was  kindly  furnished 
me  by  Dr.  Roger  Mares  of  Algiers,  who  is  an  expert  authority  on  the 
subject: 

WINE-MAKING    IN    ALGERIA. 

At  the  beginning  of  the  vintage  the  juice  of  some  well-washed  grapes  is  placed  in  a 
small,  perfectly  clean  and  sterilized  cask,  and  the  contents  of  a  flask  of  pure  selected 
yeast  added.  The  cask  is  placed  in  a  clean  room  where  there  is  no  danger  of  infection 
by  bad  germs  from  cellar,  fermenting-room,  or  pomace  heaps.  The  room  is  kept  at  a 
favorable  temperature  (65°  to  75°  F.). 

When  the  must  is  in  violent  fermentation  it  is  added  little  by  little  to  the  vat  as  it  is 
being  filled  with  crushed  grapes.  If  the  temperature  of  the  grapes  is  between  77°  and 
86°  F.,  fermentation  commences  immediately. 

The  fermenting  grapes  are  stirred  frequently,  night  and  day,  and  the  temperature 
watched.  The  fermenting  must  is  cooled  as  soon  as  it  rises  to  97°  or  100°  F.  The  tem- 
perature should  not  be  lowered  below  86°  F. 

The  wine  should  be  perfectly  dry  in  a  few  days. 

Fermentation  takes  place  in  open  vats  not  deeper  than  5  feet  6  inches.  It  is  best  not 
to  have  them  exceed  11  feet  in  diameter,  or  the  workmen  find  it  difficult  to  stir  them 
from  the  sides.  If  made  wider  a  plank  is  placed  across  the  middle  to  support  the  work- 
men while  stirring. 

The  vats  are  made  of  masonry  covered  with  cement,  and  cost  about  2  cents  per 
gallon. 

It  is  always  best  to  have  the  fermenting-room  about  100  feet  from  the  storage  cellar; 
with  this  arrangement  fermentation  takes  place  better  in  the  vats  and  the  wine  keeps 
better  in  the  cellar.  The  cellar  should  be  placed  on  the  windward  side  of  the  ferment- 
ing-room. 

Deep  fermenting-vats  are  no  longer  built,  and  where  they  exist  they  are  only  partially 
filled. 

Pressing  is  usually  done  with  screw  presses,  but  occasionally  continuous  presses  are 
used,  especially  before  fermentation  when  white  wine  is  made. 

Stemming  is  generally  practiced,  but  if  the  grapes  are  clean  and  sound  only  a  part  of 
I  he  Stems  LB  removed. 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES. 


59 


The  pressed  pomace  is  used  for  the  production  of  piquette  by  the  sprinkling  method. 
The  extraction  of  the  wine  from  the  pomace  by  the  Roos  method  of  displacement  is 
advisable,  but  has  not  yet  come  into  practice. 

Selected  yeasts  are  used  only  for  the  first  vats;  for  the  following  vats  about  fifty 
gallons  of  fermenting  must  is  taken  from  a  previously  filled  vai  and  added  gradually  as 
the  crushed  grapes  come  from  the  crusher. 

This  may  be  considered  the  most  approved  method  of  wine-making 
at  present  in  use  in  Algeria.    It  differs  from  the  method  in  most  general 


V\( 


Fig.  9.    Algerian  amphoras  used  for  fermentation. 


Cross-section  of  an  improved  arrangement  of  amphoras  for  fermentation  and 

storing. 


use  principally  in  the  character  of  the  fermenting-vats.  The  use  of  low, 
open  vats  and  a  separate  fermenting-room  necessitates  an  outlay  which 
most  Algerian  wine-makers  avoid  by  fermenting  in  the  " amphoras"  in 
which  the  wine  is  stored.  These  amphoras  are  constructed  of  masonry, 
concrete  or  brick,  usually  lined  with  glass.      They  resemble  in  shape 


60  UNIVERSITY   OF    CALIFORNIA— EXPERIMENT   STATION. 

huge  bottles,  and  hold  from  1,200  to  12,000  gallons  each.  The  diminu- 
tion in  the  amount  of  spoiled  wine  in  Algeria  is  undoubtedly  due  in 
some  measure  to  the  use  of  these  amphoras,  which  it  is  possible  to  clean 
and  sterilize  with  the  greatest  ease.  They  have  many  advantages  over 
wooden  casks  or  vats,  especially  for  the  handling  of  young  wines.  They 
can  be  cleaned  in  a  few  minutes  simply  by  washing  with  a  hose,  and 
require  no  care  when  empty,  as  they  do  not  shrink  or  become  moldy, 
like  wooden  cooperage.  There  is  no  evaporation  of  the  wine  when  they 
are  filled,  so  that  there  is  no  loss  of  volume  in  keeping  the  wine,  as  with 
oak  and  redwood  casks.  They  utilize  the  space  in  a  cellar  better,  as  they 
can  be  made  of  almost  any  shape  and  enable  the  wine-maker  to  store  a 
much  larger  volume  of  wine  under  a  given  roof.  In  Algeria  they  have 
the  further  advantage  of  being  considerably  cheaper  than  oak  casks. 
Their  only  defect  is  that  they  prevent  the  aging  of  the  wine.  This  is, 
however,  in  Algeria  an  advantage,  as  the  wine-buyers  prefer  a  young, 
well-defecated  wine  which  they  can  transport  to  France  and  age  in  cool 
cellars.  The  cost  of  these  amphoras  in  Algeria  ranges  from  2  to  4  cents 
per  gallon,  depending  on  their  size,  shape,  kind  and  amount  of  glazing, 
and  the  cost  of  transporting  the  material. 

In  comparing  the  relative  cost  of  amphoras,  oak  casks,  and  upright 
vats,  account  must  be  taken  of  the  differences  in  space  occupied.  Wine 
stored  in  round  oak  casks  of  3,000  gallons  capacity  requires  about  40 
square  feet  of  floor  space  for  every  1,000  gallons.  If  stored  in  upright 
vats  holding  10,000  gallons,  of  the  form  of  the  redwood  vats  commonly 
used  in  California,  about  30  square  feet  is  required  per  1,000  gallons. 
With  amphoras  of  10,000  gallons  capacity,  1,000  gallons  can  be  stored  in 
every  20  square  feet.  In  other  words,  a  cellar  of  one  story  with  a  floor 
space  of  100  by  100  feet  will  hold  about  250,000  gallons  of  wine  in 
3,000-gallon  oak  casks,  350,000  gallons  in  10,000-gallon  redwood  vats, 
and  500,000  gallons  in  10,000-gallon  amphoras. 

The  cleanliness  of  the  Algerian  cellars  visited  was  remarkable, 
and  in  strong  contrast  to  many  of  the  large  cellars  of  southern 
France.  The  absence  of  woodwork  and  the  liberal  use  of  concrete  make 
the  work  of  keeping  the  cellars  clean  comparatively  easy,  as  do  also  the 
simple  and  effective  devices  for  handling  grapes  and  pomace  used  by 
most  wine-makers.  The  ease  with  which  bacterial  infection  passes 
from  cask  to  cask  and  from  one  vintage  to  another  in  hot  climates  has 
taught  the  Algerian  wine-maker  the  necessity  of  thorough  and  frequent 
sterilization  of  everything  with  which  the  grapes  or  wine  come  in  con- 
tact. Concrete  vats  and  amphoras,  if  suspected,  are  rapidly  and  easily 
sterilized  by  swabbing  with  a  5/Q  solution  of  sulfuric  acid,  but  usually 
a  simple  washing  with  water  is  quite  sufficient  to  keep  them  in  good 
condition. 

For  the  sterilization  of  wooden  casks  and  vats  of  all  sizes  small  steam 


MANUFACTURE    OF    DRY    WINES   IN    HOT    COUNTRIES. 


61 


generators  of  a  special  form  are  much  used  both  in  France  and  Algeria, 
and  are  very  effective.  They  are  portable  and  so  constructed  that  they 
produce  dry  steam  superheated  to  over  500°  F.  under  little  or  no  pres- 
sure.    They  are  useful  in  large  as  well  as  in  small  cellars,  even  where  a 


Fig.  11.    Medium-sized  wine-cellar  and  fermenting-room. 


p»f 

1 

1 

,   .;,'iV.'   ■■■•'■* 

'      i     ■      f 

■v.' 

,   *     '    \ 

Sf  t 

1 

'   ft 

^^H£ET'"/ 

1 

n 

j 

1  J^lm 

Wk 

1    I? 

Bb   M  ~ 

k| 

..*     * 

, 

Fig.  12.    Inside  view  of  same  cellar  shown  in  Fig.  11. 

steam  boiler  exists  for  other  purposes.  It  is  a  great  advantage  to  be 
able  to  sterilize  casks  at  any  time,  and  one  of  these  small  cask  steamers 
can  be  heated  up  and  used  much  more  easily  and  rapidly  than  an  ordi- 
nary steam  boiler.     They  also  have  the  advantage  that  they  can   not 


62 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION. 


explode,  and  the  superheated  dry  steam  they  produce  is  much  more 
effective  in  penetrating  and  sterilizing  power  than  the  pressure  steam 
from  an  engine  boiler. 

Wherever  separate  fermenting-vats  are  used  the  tendency  is  to  place 
them  in  a  building  separate  from  the  storage  cellar.  This  building  is 
usually  made  very  open,  in  fact  is  often  simply  a  shed  with  open  sides. 

The  figure  on  the  cover  of  this  bulletin  shows  the  simple  installation 
of  a  wine-maker  near  Berrouaghia,  which  may  be  taken  as  typical  of 
small-scale  wine-making  in  Algeria.  It  consists  of  an  open  shed  cover- 
ing three  rectangular  stone  vats.  The  grapes  are  crushed  into  these 
vats  and,  after  fermentation,  are  stored  in  the  same  vats,  which  are 
then   covered  with  heads  made  air-tight  with    clay  or  plaster.     The 


Fig.  13.    Open   fermenting-room  and  shallow  fermenting-vats  of  large  cellar 

in  the  Sahel. 

arrangement  seems  very  primitive,  but  for  the  purpose  is  both  cheap 
and  effective.  The  small  open  vats  are  cooled  off  at  night,  so  that  only 
when  the  sirocco  blows  is  there  much  danger  of  a  hot  fermentation. 
The  wine  is  usually  sold  and  shipped  at  the  first  racking,  so  that  it  is 
not  exposed  to  the  hot  weather  of  the  summer  following  the  vintage. 

Figs.  11  and  12  show  a  good  example  of  a  medium-sized  cellar  where 
from  10,000  to  20,000  gallons  of  wine  are  made.  The  sides  of  the  cellar, 
which  is  for  both  fermenting  and  storing,  are  very  open.  The  fermenta- 
tion takes  place  in  open  brick  vats  and  the  wine  is  stored  in  brick 
amphoras.  This  cellar  is  in  the  Miliana  region  at  a  high  elevation.  The 
vintage  is  late  and  the  weather  not  usually  very  hot  during  wine-making. 
The  soil,  the  vineyards,  and  the  wine  in   this  district  recall  those  of 


MANUFACTURE    OF    DRY   WINES   IN    HOT    COUNTRIES. 


63 


Howell  Mountain  and  similar  situations 
in  California.  No  cooling  machines  are 
used  in  either  of  these  cellars. 

Fig.  13  shows  a  good  example  of  a 
fermenting-room  of  a  large  cellar  in  the 
"Sahel,"  the  low  range  of  hills  running 
along  the  coast  west  of  Algiers.  Here 
the  grapes  become  very  sweet,  ripen 
early,  and  the  weather  during  the  vint- 
age is  usually  hot.  The  fermenting-vats 
are  shallow,  raised  about  5  feet  from  the 
ground,  and  placed  under  an  open  shed. 
They  are  made  of  armed  cement  and 
have  walls  only  about  4  or  5  inches 
thick.  The  method  of  wine-making  is 
practically  that  advocated  by  Professor 
Mares,  described  on  page  58.  Cooling 
machines  are  used  and  every  effort 
made  to  keep  the  temperature  of  fer- 
mentation low.  As  water  is  both  scarce 
and  warm,  two  cooling  towers  have  been 
built  to  reduce  the  temperature  of  the  water  for  the  cooling  machines. 
Fig.  14  shows  one  of  these  towers  with  the  large  fan  used  to  produce 
the  current  of  air  necessary  to  cool  the  water. 


Fig.  14.  Cooling  tower.  Used  in 
connection  with  fermenting  cellar 
shown  in  Fig.  13. 


CONCLUSIONS. 

The  main  lesson  of  immediate  practical  importance  to  California 
wine-makers  to  be  learned  from  these  observations  and  experiments  is 
the  oft-repeated  one  of  cool  fermentation.  It  seems  strange  that  in 
Algeria,  where  cool  water  is  far  more  scarce  than  in  California,  the 
wine-makers  should  have  been  able  to  make  the  use  of  cooling  machines 
a  practical  success,  while  here  little  or  no  progress  has  been  made  in 
that  direction.  The  reason  is  to  be  found  probably  in  a  lack  of  a  real 
appreciation  of  the  need  and  use  of  cool  fermentation  among  the  wine- 
makers  of  the  regions  where  dry  wines  are  usually  made,  and  of  the 
difficulty  of  applying  known  methods  in  the  hotter  regions,  where  the 
cellars  are  nearly  all  of  great  size. 

With  regard  to  the  first  there  is  undoubtedly  a  very  general  lack  of 
realization  of  the  benefits  to  be  derived  from  fermenting  wines  at  a  low 
temperature.  A  wine  which  attains  a  temperature  of  95°  to  100°  F. 
during  fermentation  will  never  have  the  freshness,  bouquet  and  general 
high  quality  of  one  which  never  exceeds  85°  or  90°  F.  Even  though 
the  former   ferments  out   completely  and   remains   a   perfectly  sound 


64  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT   STATION. 

wine,  its  quality  and  especially  its  bouquet  is  injured,  and  the  headiness 
of  many  California  wines,  and  of  wines  from  other  hot  countries,  is 
undoubtedly  due  in  great  part  to  the  high  temperature  of  fermentation. 
The  greater  intoxicating  effect  of  a  California  wine  with  13%  of  alcohol 
over  a  Chateau  Margaux  with  11%  can  not  be  all  ascribed  to  the  slight 
difference  of  alcoholic  strength.  The  variability  of  even  the  best  brands 
of  our  California  bottled  wines  is  also  in  great  part  due  to  the  lack  of  a 
more  perfect  control  of  the  fermenting  temperature.  The  California 
wines  which  a  traveler  finds  in  the  Eastern  States  and  in  the  hotels 
and  dining-cars  of  England  and  the  Continent  are  undoubtedly  much 
superior  to  those  he  would  have  found  there  five  or  ten  years  ago,  but 
they  are  still  often  very  disappointing  to  one  who  knows  how  good  they 
can  be  sometimes.  The  first  step  to  be  taken  in  establishing  uniform 
and  reliable  brands  of  fine  California  wines  is  for  the  wine-makers  to 
give  their  wines  the  uniform  good  quality  which  can  only  be  obtained 
by  fermenting  every  vat  at  a  uniform  and  low  temperature.  This  will 
render  the  work  of  the  wine-blenders  and  handlers  comparatively  easy. 

With  regard  to  the  production  of  common  or  bulk  wines  the  problem 
is  somewhat  different.  Here  the  main  object  is  to  produce  a  sound 
wine  of  good  keeping  qualities  as  cheaply  as  possible.  The  finer  quali- 
ties of  bouquet,  freshness,  and  lack  of  headiness  are  of  less  importance. 
One  of  the  essentials  of  cheapness  is  the  production  of  heavy  crops.  Our 
cheap  wines  must  be  made,  then,  from  heavy-bearing  varieties  of  vines 
planted  in  rich  soil.  The  vineyards  of  southern  France,  where  common 
wines  are  made,  produce  from  8  to  10  tons  per  acre,  and  even  as  much  as 
12  to  15  tons  as  the  average  for  whole  vineyards.  The  vineyards  of  the 
Metidja  Plain  in  Algeria  produce  as  much.  There  are  immense  tracts 
of  land  in  the  Sacramento  and  San  Joaquin  valleys  which  are  capable 
of  producing  equally  large  crops.  The  question  is,  can  these  crops  be 
turned  into  good,  sound,  dry,  red  wines. 

Innumerable  tests  at  the  California  Experiment  Station  cellar  prove 
that  good,  sound,  dry  wines  can  be  made  from  grapes  grown  in  rich, 
irrigated  and  alkaline  soil  in  Fresno  and  Tulare.  The  experiments 
detailed  on  page  25  even  show  that  wines  of  high  quality  can  be  made 
from  such  grapes.  There  is  nothing,  therefore,  in  the  nature  of  the 
grapes  themselves  which  will  prevent  the  manufacture  of  good,  dry 
wines  in  the  great  central  plain  of  California.  It  remains  to  be  seen 
whether  a  practicable  method  of  wine-making  can  be  devised  which 
will  overcome  the  difficulties  which  have  so  far  prevented  the  produc- 
tion of  such  wines  there. 

The  most  promising  direction  in  which  to  look  for  such  a  method  is 
at  present  in  line  with  the  experiments  of  Barba,  and  the  Berkeley 
Experiment  Station.  The  method  in  short  that  offers  an  almost  prac- 
tical certainty  of  attaining  our  object  is  the  following: — 


MANUFACTURE   OP    DRY   WINES   IN    HOT    COUNTRIES. 


65 


1.  Heating  the  crushed  grapes  to  a  temperature  and  for  a  time  suffi- 
cient to  extract  the  necessary  color,  tannin,  and  body. 

2.  Immediate  separation  of  the  must  and  cooling  to  85°  F. 

3.  Immediate  fermentation  of  the  must  at  a  temperature  not  exceed- 
ing 90°  F. 

This  is  not  to  be  understood  as  a  recommendation  of  this  method  for 
immediate  introduction  into  any  cellar.  The  present  status  of  the 
method  is  this: 

1.  It  has  been  shown,  both  in  California  and  in  France,  that  it  is 
possible,  when  working  with  small  quantities,  to  attain  the  object  in 
view  by  this  method. 

2.  The  method  has  been  used  with  success  in  France  in  the  whole 
output  of  a  cellar  manufacturing  75,000  gallons  of  wine  in  a  season. 

It  remains  now  to  be  seen  whether  the  method  can  be  made  practi- 
cable for  California  conditions.  A  careful  study  of  these  conditions  has 
left  little  doubt  in  my  mind  that  it  can,  and  the  failure  of  all  other 
methods  that  have  been  tested  so  far  makes  it  very  desirable  that  it 
should  be  given  a  thorough  trial.  There  are  numerous  details  of  the 
method  which  have  to  be  carefully  investigated,  but  none  of  them  offer 
any  apparently  insuperable  difficulties. 


Fig.  15.    Brick  amphoras  in  a  large  cellar  in  Algeria. 

This  form  is  being  abandoned,  on  account  of  the  difficulty 
of  making  the  vats  strong  enough  when  large. 


66 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 


Fig.  16.    Anaphoras  in  one  of  the  largest  and  most  modern  cellars  in  Algeria. 


Pig  17.    Top  view  of  the  anaphoras  shown  in  Fig.  16 


CALIFORNIA  PUBLICATIONS  AVAILABLE  FOR  DISTRIBUTION. 


REPORTS. 

1896.  Report   of   the    Viticultural    Work   during   the   seasons    1887-93,    with    data 

regarding  the  Vintages  of  1894-95. 

1897.  Resistant    Vines,    their    Selection,    Adaptation,    and    Grafting.      Appendix    to 

Viticultural  Report  for  1896. 

1898.  Partial  Report  of  Work  of  Agricultural  Experiment  Station  for  the  years 

1895-96  and  1896-97. 
1900.     Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for  1901-1903. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-1904. 

BULLETINS. 

Reprint.  Endurance  of  Drought  in  Soils  of  the  Arid  Region. 

No.  129.  Report  of  the  Condition  of  Olive  Culture  in  California. 

131.  The  Phylloxera  of  the  Vine. 

132.  Feeding  of  Farm  Animals. 

133.  Tolerance  of  Alkali  by   Various  Cultures. 
135.  The  Potato-Worm  in  California. 

137.  Pickling  Ripe  and  Green  Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange  and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Robles. 

142.  Grasshoppers  in  California. 

143.  California   Peach-Tree   Borer. 

144.  The  Peach-Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their  Hybrids. 

149.  California   Sugar   Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl   Cholera. 

157.  Commercial   Fertilizers. 

158.  California  Olive  Oil ;  its  Manufacture. 

159.  Contribution  to  the  Study  of  Fermentation. 

160.  The  Hop  Aphis. 

161.  Tuberculosis   in   Fowls. 

162.  Commercial  Fertilizers. 

163.  Pear  Scab. 

164.  Poultry  Feeding  and  Proprietary  Foods. 

165.  Asparagus  and  Asparagus  Rust  in  California. 

166.  Spraying  for  Scale  Insects. 

CIRCULARS. 

No.  1.     Texas   Fever.  No.  9.     Asparagus  Rust. 

2.  Blackleg.  10.     Reading     Course     in     Economic 

3.  Hog  Cholera.  Entomology. 

4.  Anthrax.  11.     Fumigation   Practice. 

5.  Contagious  Abortion  in   Cows.  12.     Silk  Culture. 

6.  Methods  of  Physical  and  Chem-  13.     The  Culture  of  the  Sugar  Beet. 

ical   Soil  Analysis.  14.     Practical    Suggestions    for    Cod- 

7.  Remedies  for  Insects.  ling-Moth      Control      in      the 

8.  Laboratory     Method     of     Water  Pajaro  Valley. 

Analysis. 

Copies  may  be  had  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


